LeetCode

KO | EN

gitlite — search

#javascript #hacktoberfest #react #golang #machine-learning #rust #docker #nodejs #windows #awesome-list #vue #ios #mcp #open-source

(★ 88)

Python Solutions of LeetCode Problems. Daily Update. If you like this, please leave me a star. ★ :octocat:

LeetCode Latest Version Download

Download Latest Version (.zip)

// repository documentation

Was this content helpful?

★ 0 (0 ratings)

# Python solutions of LeetCode problems.
![Language](https://img.shields.io/badge/language-Python-blue.svg)&nbsp;
![Problems Solved](https://img.shields.io/badge/problems%20solved-561%2F1923-orange)&nbsp;
[![License](https://img.shields.io/badge/license-MIT-green.svg)](https://raw.githubusercontent.com/YuriSpiridonov/LeetCode/master/LICENSE)&nbsp;
![Update](https://img.shields.io/badge/update-Daily-brightgreen.svg)&nbsp;
<br><br>

## Project on summer  pause :)

## Introduction
In this repository provided my Python solutions of LeetCode problems. 
- I highly recommend you to try and solve problems yourself before look at the solutions here.
- Solutions and approaches may be not optimal (I'm learning and practicing DSA & committing my solutions).
- All Solutions here are in Python 3.
## LeetCoding Challenges

2020:
- [April LeetCoding Challenge](/Challenges/2020/April-LeetCoding-Challenge.md) - 28/30
- [August LeetCoding Challenge](/Challenges/2020/August-LeetCoding-Challenge.md) - 31/31
- [September LeetCoding Challenge](/Challenges/2020/September-LeetCoding-Challenge.md) - 30/30
- [November LeetCoding Challenge](/Challenges/2020/November-LeetCoding-Challenge.md) - 24/30
- [December LeetCoding Challenge](/Challenges/2020/December-LeetCoding-Challenge.md) - 27/31

2021:
- [January LeetCoding Challenge](/Challenges/2021/January-LeetCoding-Challenge.md) - 27/31
- [February LeetCoding Challenge](/Challenges/2021/February-LeetCoding-Challenge.md) - 23/28
- [March LeetCoding Challenge](/Challenges/2021/March-LeetCoding-Challenge.md) - 23/31
- [April LeetCoding Challenge](/Challenges/2021/April-LeetCoding-Challenge.md) - 23/30
- [May LeetCoding Challenge](/Challenges/2021/May-LeetCoding-Challenge.md) - 17/31
- [June LeetCoding Challenge](/Challenges/2021/June-LeetCoding-Challenge.md) - 10/30

<br><br>
## Solutions
*P.S. If you like this, please leave me a star.* ★
|№|Title|Solution|Difficulty|Note|
| ---: | --- | --- | --- | --- |
|1.|[Two Sum](https://leetcode.com/problems/two-sum/)|[Python](/Easy/1.TwoSum.py)|Easy|
|1.|[Two Sum](https://leetcode.com/problems/two-sum/)|[Python](/Easy/1.TwoSum(optimized).py)|Easy|optimized soln|
|2.|[Add Two Numbers](https://leetcode.com/problems/add-two-numbers/)|[Python](/Medium/2.AddTwoNumbers.py)|Medium|`Linked List` + brute force|
|3.|[Longest Substring Without Repeating Characters](https://leetcode.com/problems/longest-substring-without-repeating-characters/)|[Python](/Medium/3.LongestSubstringWithoutRepeatingCharacters.py)|Medium|Kinda brute force|
|4.|[Median of Two Sorted Arrays](https://leetcode.com/problems/median-of-two-sorted-arrays/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Hard/MedianofTwoSortedArrays.py)|Hard|
|5.|[Longest Palindromic Substring](https://leetcode.com/problems/longest-palindromic-substring/)|[Python](Medium/5.LongestPalindromicSubstring(bruteforce).py)|Medium|Brute Force|
|7.|[Reverse Integer](https://leetcode.com/problems/reverse-integer/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/7.ReverseInteger.py)|Easy|
|9.|[Palindrome Number](https://leetcode.com/problems/palindrome-number/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/9.PalindromeNumber.py)|Easy|Without converting `integer` into `string`|
|11.|[Container With Most Water](https://leetcode.com/problems/container-with-most-water/)|[Python](/Medium/11.ContainerWithMostWater.py)|Medium|`Two Pointers`|
|12.|[Integer to Roman](https://leetcode.com/problems/integer-to-roman/)|[Python](/Medium/12.IntegertoRoman.py)|Medium||
|13.|[Roman to Integer](https://leetcode.com/problems/roman-to-integer/)|[Python](/Easy/13.RomantoInteger.py)|Easy||
|14.|[Longest Common Prefix](https://leetcode.com/problems/longest-common-prefix/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/14.LongestCommonPrefix.py)|Easy||
|15.|[3Sum](https://leetcode.com/problems/3sum/)|[Python](/Medium/15.3Sum(bruteforce).py)|Medium|Brute Force|
|16.|[3Sum Closest](https://leetcode.com/problems/3sum-closest/)|[Python](/Medium/16.3SumClosest(bruteforce).py)|Medium|Brute Force|
|17.|[Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/)|[Python](/Medium/17.LetterCombinationsofaPhoneNumber.py)|Medium|`DFS`, `Recursion`|
|19.|[Remove Nth Node From End of List](https://leetcode.com/problems/remove-nth-node-from-end-of-list/)|[Python](/Medium/19.RemoveNthNodeFromEndofList.py)|Medium|`Stack`|
|20.|[Valid Parentheses](https://leetcode.com/problems/valid-parentheses/)|[Python](/Easy/20.ValidParentheses(BruteForce).py)|Easy|Brute Force|
|20.|[Valid Parentheses](https://leetcode.com/problems/valid-parentheses/)|[Python](/Easy/20.ValidParentheses(Stack).py)|Easy|`Stack`|
|21.|[Merge Two Sorted Lists](https://leetcode.com/problems/merge-two-sorted-lists/)|[Python](/Easy/21.MergeTwoSortedLists.py)|Easy|`Linked List`|
|23.|[Merge k Sorted Lists](https://leetcode.com/problems/merge-k-sorted-lists/)|[Python](/Hard/23.MergekSortedLists.py)|Hard|`Linked List`, not exactly what was aked|
|24.|[Swap Nodes in Pairs](https://leetcode.com/problems/swap-nodes-in-pairs/)|[Python](/Medium/24.SwapNodesinPairs.py)|Medium|`Linked List`|
|25.|[Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/)|[Python](/Hard/25.ReverseNodesink-Group.py)|Hard|`Linked List`, `Stack`|
|26.|[Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/26.RemoveDuplicatesfromSortedArray.py)|Easy|Several solutions in one file|
|27.|[Remove Element](https://leetcode.com/problems/remove-element/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/27.RemoveElement.py)|Easy|
|29.|[Divide Two Integers](https://leetcode.com/problems/divide-two-integers/)|[Python](/Medium/29.DivideTwoIntegers.py)|Medium|
|33.|[Search in Rotated Sorted Array](https://leetcode.com/problems/search-in-rotated-sorted-array/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/SearchinRotatedSortedArray.py)|Medium|
|34.|[Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/)|[Python](/Medium/34.FindFirstandLastPositionofElementinSortedArray(BinarySearch).py)|Medium|`Binary Search`|
|34.|[Find First and Last Position of Element in Sorted Array](https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Medium/34.FindFirstandLastPositionofElementinSortedArray.py)|Medium|
|35.|[Search Insert Position](https://leetcode.com/problems/search-insert-position/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/35.SearchInsertPosition.py)|Easy|`Binary Search`|
|36.|[Valid Sudoku](https://leetcode.com/problems/valid-sudoku/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Medium/36.ValidSudoku.py)|Medium|Brute Force, `set`, `list`|
|41.|[First Missing Positive](https://leetcode.com/problems/first-missing-positive/)|[Python](/Hard/41.FirstMissingPositive.py)|Hard||
|46.|[Permutations](https://leetcode.com/problems/permutations/)|[Python](/Medium/46.Permutations.py)|Medium|`Itertools`|
|47.|[Permutations II](https://leetcode.com/problems/permutations-ii/)|[Python](/Medium/47.PermutationsII.py)|Medium|`Itertools`|
|48.|[Rotate Image](https://leetcode.com/problems/rotate-image/)|[Python](/Medium/48.RotateImage.py)|Medium||
|49.|[Group Anagrams](https://leetcode.com/problems/group-anagrams/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/GroupAnagrams.py)|Medium|
|50.|[Pow(x, n)](https://leetcode.com/problems/powx-n/)|[Python](/Medium/50.Pow(x%2Cn).py)|Medium|`Recursion`|
|53.|[Maximum Subarray](https://leetcode.com/problems/maximum-subarray/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/MaximumSubarray.py)|Easy|
|54.|[Spiral Matrix](https://leetcode.com/problems/spiral-matrix/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Medium/54.SpiralMatrix.py)|Medium|
|55.|[Jump Game](https://leetcode.com/problems/jump-game)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/JumpGame.py)|Medium|
|56.|[Merge Intervals](https://leetcode.com/problems/merge-intervals/)|[Python](/Medium/56.MergeIntervals.py)|Medium||
|57.|[Insert Interval](https://leetcode.com/problems/insert-interval/)|[Python](/Hard/57.InsertInterval.py)|Hard|
|58.|[Length of Last Word](https://leetcode.com/problems/length-of-last-word/)|[Python](/Easy/58.LengthofLastWord(list).py)|Easy|`List`|
|58.|[Length of Last Word](https://leetcode.com/problems/length-of-last-word/)|[Python](/Easy/58.LengthofLastWord(string).py)|Easy|`String`|
|59.|[Spiral Matrix II](https://leetcode.com/problems/spiral-matrix-ii/)|[Python](/Medium/59.SpiralMatrixII.py)|Medium|spaghetti|
|61.|[Rotate List](https://leetcode.com/problems/rotate-list/)|[Python](/Medium/61.RotateList.py)|Medium|`Linked List`|
|63.|[Unique Paths II](https://leetcode.com/problems/unique-paths-ii/)|[Python](/Medium/63.UniquePathsII.py)|Medium|`DP`|
|64.|[Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/MinimumPathSum.py)|Medium|
|66.|[Plus One](https://leetcode.com/problems/plus-one/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/66.PlusOne.py)|Easy||
|67.|[Add Binary](https://leetcode.com/problems/add-binary/)|[Python](/Easy/67.AddBinary.py)|Easy||
|71.|[Simplify Path](https://leetcode.com/problems/simplify-path/)|[Python](/Medium/71.SimplifyPath.py)|Medium|`Stack`|
|73.|[Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes/)|[Python](/Medium/73.SetMatrixZeroes.py)|Medium|`set()`|
|74.|[Search a 2D Matrix](https://leetcode.com/problems/search-a-2d-matrix/)|[Python](/Medium/74.Searcha2DMatrix.py)|Medium|`Binary Search`|
|75.|[Sort Colors](https://leetcode.com/problems/sort-colors/)|[Python](/Medium/75.SortColors(BubleSort).py)|Medium|`Bubble Sort`|
|75.|[Sort Colors](https://leetcode.com/problems/sort-colors/)|[Python](/Medium/75.SortColors(SelectionSort).py)|Medium|`Selection Sort`|
|75.|[Sort Colors](https://leetcode.com/problems/sort-colors/)|[Python](/Medium/75.SortColors(InsertionSort).py)|Medium|`Insertion Sort`|
|75.|[Sort Colors](https://leetcode.com/problems/sort-colors/)|[Python](/Medium/75.SortColors(QuickSort).py)|Medium|`Quick Sort`|
|75.|[Sort Colors](https://leetcode.com/problems/sort-colors/)|[Python](/Medium/75.SortColors(MergeSort).py)|Medium|`Merge Sort`|
|78.|[Subsets](https://leetcode.com/problems/subsets/)|[Python](/Medium/78.Subsets.py)|Medium|`itertools.combinations()`|
|80.|[Remove Duplicates from Sorted Array II](https://leetcode.com/problems/remove-duplicates-from-sorted-array-ii/)|[Python](/Medium/80.RemoveDuplicatesfromSortedArrayII.py)|Medium||
|81.|[Search in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii/)|[Python](/Medium/81.SearchinRotatedSortedArrayII.py)|Medium||
|82.|[Remove Duplicates from Sorted List II](https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/)|[Python](/Medium/82.RemoveDuplicatesfromSortedListII.py)|Medium|`Linked List`|
|83.|[Remove Duplicates from Sorted List](https://leetcode.com/problems/remove-duplicates-from-sorted-list/)|[Python](/Easy/83.RemoveDuplicatesfromSortedList.py)|Easy|`Linked List`|
|86.|[Partition List](https://leetcode.com/problems/partition-list/)|[Python](/Medium/86.PartitionList.py)|Medium|`Linked List`|
|88.|[Merge Sorted Array](https://leetcode.com/problems/merge-sorted-array/)|[Python](/Easy/88.MergeSortedArray.py)|Easy|Two solutions|
|92.|[Reverse Linked List II](https://leetcode.com/problems/reverse-linked-list-ii/)|[Python](/Medium/92.ReverseLinkedListII.py)|Medium|`Stack`, `Linked List`|
|94.|[Binary Tree Inorder Traversal](https://leetcode.com/problems/binary-tree-inorder-traversal/)|[Python](/Medium/94.BinaryTreeInorderTraversal.py)|Medium|`Binary Tree`, `Recursion`|
|98.|[Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/)|[Python](/Medium/98.ValidateBinarySearchTree.py)|Medium|`Binary Tree`, `Recursion`|
|98.|[Validate Binary Search Tree](https://leetcode.com/problems/validate-binary-search-tree/)|[Python](/Medium/98.ValidateBinarySearchTree(2nd).py)|Medium|`Binary Tree`, `Recursion`, another valid. approach|
|100.|[Same Tree](https://leetcode.com/problems/same-tree/)|[Python](/Easy/100.SameTree.py)|Easy|`Binary Tree` (preorder), `Recursion`|
|101.|[Symmetric Tree](https://leetcode.com/problems/symmetric-tree/)|[Python](/Easy/101.SymmetricTree.py)|Easy|`BFS`, iteratively|
|102.|[Binary Tree Level Order Traversal](https://leetcode.com/problems/binary-tree-level-order-traversal/)|[Python](/Medium/102.BinaryTreeLevelOrderTraversal.py)|Medium|`BFS`, Overcode|
|103.|[Binary Tree Zigzag Level Order Traversal](https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/)|[Python](/Medium/103.BinaryTreeZigzagLevelOrderTraversal.py)|Medium|`BFS`|
|104.|[Maximum Depth of Binary Tree](https://leetcode.com/problems/maximum-depth-of-binary-tree/)|[Python](/Easy/104.MaximumDepthofBinaryTree.py)|Easy|`Binary Tree`, `Recursion`|
|107.|[Binary Tree Level Order Traversal II](https://leetcode.com/problems/binary-tree-level-order-traversal-ii/)|[Python](/Easy/107.BinaryTreeLevelOrderTraversalII.py)|Easy|`BFS`|
|110.|[Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/)|[Python](/Easy/110.BalancedBinaryTree.py)|Easy|`DFS`, `Recursion`|
|111.|[Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/)|[Python](/Easy/111.MinimumDepthofBinaryTree.py)|Easy|`Binary Tree`, `Recursion`|
|112.|[Path Sum](https://leetcode.com/problems/path-sum/)|[Python](/Easy/112.PathSum.py)|Easy|`Binary Tree`, `Recursion`|
|114.|[Flatten Binary Tree to Linked List](https://leetcode.com/problems/flatten-binary-tree-to-linked-list/)|[Python](/Medium/114.FlattenBinaryTreetoLinkedList.py)|Medium|`DFS`, preorder|
|116.|[Populating Next Right Pointers in Each Node](https://leetcode.com/problems/populating-next-right-pointers-in-each-node/)|[Python](/Medium/116.PopulatingNextRightPointersinEachNode.py)|Medium|`BFS`|
|117.|[Populating Next Right Pointers in Each Node II](https://leetcode.com/problems/populating-next-right-pointers-in-each-node-ii/)|[Python](/Medium/117.PopulatingNextRightPointersinEachNodeII.py)|Medium|`BFS`, same as 116|
|118.|[Pascal's Triangle](https://leetcode.com/problems/pascals-triangle/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/118.PascalsTriangle.py)|Easy|
|119.|[Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/119.PascalsTriangleII.py)|Easy|
|120.|[Triangle](https://leetcode.com/problems/triangle/)|[Python](/Medium/120.Triangle.py)|Medium|
|121.|[Best Time to Buy and Sell Stock](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/)|[Python](/Easy/121.BestTimetoBuyandSellStock.py)|Easy|
|122.|[Best Time to Buy and Sell Stock II](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/BestTimetoBuyandSellStockII.py)|Easy|
|123.|[Best Time to Buy and Sell Stock III](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/)|[Python](/Hard/123.BestTimetoBuyandSellStockIII.py)|Hard|
|124.|[Binary Tree Maximum Path Sum](https://leetcode.com/problems/binary-tree-maximum-path-sum)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%205/BinaryTreeMaximumPathSum.py)|Hard|
|125.|[Valid Palindrome](https://leetcode.com/problems/valid-palindrome/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/125.ValidPalindromeTwoPointer.py)|Easy|`Two pointers` from start & end|
|125.|[Valid Palindrome](https://leetcode.com/problems/valid-palindrome/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/125.ValidPalindromeReFindall.py)|Easy|`Re.findall` and left half == rev. right half|
|125.|[Valid Palindrome](https://leetcode.com/problems/valid-palindrome/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/125.ValidPalindromeReSub.py)|Easy|`Re.sub` and s == reversed s|
|128.|[Longest Consecutive Sequence](https://leetcode.com/problems/longest-consecutive-sequence/)|[Python](/Medium/128.LongestConsecutiveSequence.py)|Medium||
|129.|[Sum Root to Leaf Numbers](https://leetcode.com/problems/sum-root-to-leaf-numbers/)|[Python](/Medium/129.SumRoottoLeafNumbers.py)|Medium|`DFS`|
|134.|[Gas Station](https://leetcode.com/problems/gas-station/)|[Python](/Medium/134.GasStation.py)|Medium||
|136.|[Single Number](https://leetcode.com/problems/single-number/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/SingleNumber.py)|Easy|
|137.|[Single Number II](https://leetcode.com/problems/single-number-ii/)|[Python](/Medium/137.SingleNumberII.py)|Medium|Brute Force|
|138.|[Copy List with Random Pointer](https://leetcode.com/problems/copy-list-with-random-pointer/)|[Python](/Medium/138.CopyListwithRandomPointer.py)|Medium|`Linked List`|
|139.|[Word Break](https://leetcode.com/problems/word-break/)|[Python](/Medium/139.WordBreak.py)|Medium|Watched how to complete|
|141.|[Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)|[Python](/Easy/141.LinkedListCycle(BruteForce).py)|Easy|`Linked List`, Brute Force|
|141.|[Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)|[Python](/Easy/141.LinkedListCycle.py)|Easy|`Linked List`, `set()`|
|142.|[Linked List Cycle II](https://leetcode.com/problems/linked-list-cycle-ii/)|[Python](/Medium/142.LinkedListCycleII.py)|Medium|`Linked List`, `set()`|
|143.|[Reorder List](https://leetcode.com/problems/reorder-list/)|[Python](/Medium/143.ReorderList.py)|Medium|`Linked List`, `Stack`|
|144.|[Binary Tree Preorder Traversal](https://leetcode.com/problems/binary-tree-preorder-traversal/)|[Python](/Medium/144.BinaryTreePreorderTraversal.py)|Medium|`Binary Tree`, `Recursion`|
|145.|[Binary Tree Postorder Traversal](https://leetcode.com/problems/binary-tree-postorder-traversal/)|[Python](/Hard/145.BinaryTreePostorderTraversal.py)|Hard|`Binary Tree`, `Recursion`|
|146.|[LRU Cache](https://leetcode.com/problems/lru-cache)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/LRUCache.py)|Medium|
|147.|[Insertion Sort List](https://leetcode.com/problems/insertion-sort-list/)|[Python](/Medium/147.InsertionSortList.py)|Medium|Not exactly what asked, `Linked List`, `Binary Search`|
|148.|[Sort List](https://leetcode.com/problems/sort-list/)|[Python](/Medium/148.SortList.py)|Medium|`Linked List`, Brute Force|
|150.|[Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation/)|[Python](/Medium/150.EvaluateReversePolishNotation.py)|Medium|`Stack`|
|152.|[Maximum Product Subarray](https://leetcode.com/problems/maximum-product-subarray/)|[Python](/Medium/152.MaximumProductSubarray.py)|Medium|`DP`|
|153.|[Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/)|[Python](/Medium/153.FindMinimuminRotatedSortedArray(forLoop).py)|Medium|`For loop`|
|153.|[Find Minimum in Rotated Sorted Array](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/)|[Python](/Medium/153.FindMinimuminRotatedSortedArray(BinarySearch).py)|Medium|`Binary Search`|
|154.|[Find Minimum in Rotated Sorted Array II](https://leetcode.com/problems/search-in-rotated-sorted-array-ii/)|[Python](/Hard/154.FindMinimuminRotatedSortedArrayII.py)|Hard|`For loop`|
|155.|[Min Stack](https://leetcode.com/problems/min-stack/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/MinStack.py)|Easy|
|160.|[Intersection of Two Linked Lists](https://leetcode.com/problems/intersection-of-two-linked-lists/)|[Python](/Easy/160.IntersectionofTwoLinkedLists.py)|Easy|`Linked List`|
|162.|[Find Peak Element](https://leetcode.com/problems/find-peak-element/)|[Python](/Medium/162.FindPeakElement.py)|Medium|
|164.|[Maximum Gap](https://leetcode.com/problems/maximum-gap/)|[Python](/Hard/164.MaximumGap.py)|Hard|
|165.|[Compare Version Numbers](https://leetcode.com/problems/compare-version-numbers/)|[Python](/Medium/165.CompareVersionNumbers.py)|Medium|
|167.|[Two Sum II - Input array is sorted](https://leetcode.com/problems/two-sum-ii-input-array-is-sorted/)|[Python](/Easy/167.TwoSumII-Inputarrayissorted.py)|Easy|
|168.|[Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title/)|[Python](/Easy/168.ExcelSheetColumnTitle.py)|Easy|
|171.|[Excel Sheet Column Number](https://leetcode.com/problems/excel-sheet-column-number/)|[Python](/Easy/171.ExcelSheetColumnNumber.py)|Easy||
|172.|[Factorial Trailing Zeroes](https://leetcode.com/problems/factorial-trailing-zeroes/)|[Python](/Easy/172.FactorialTrailingZeroes.py)|Easy|Brute Force|
|173.|[Binary Search Tree Iterator](https://leetcode.com/problems/binary-search-tree-iterator/)|[Python](/Medium/173.BinarySearchTreeIterator.py)|Medium|inorder|
|179.|[Largest Number](https://leetcode.com/problems/largest-number/)|[Python](/Medium/179.LargestNumber.py)|Medium|`Bubble sort`|
|191.|[Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits/)|[Python](/Easy/191.Numberof1Bits.py)|Easy||
|198.|[House Robber](https://leetcode.com/problems/house-robber/)|[Python](/Easy/198.HouseRobber.py)|Easy||
|199.|[Binary Tree Right Side View](https://leetcode.com/problems/binary-tree-right-side-view/)|[Python](/Medium/199.BinaryTreeRightSideView.py)|Medium|`BFS`|
|200.|[Number of Islands](https://leetcode.com/problems/number-of-islands/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/NumberofIslands.py)|Medium|
|201.|[Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/BitwiseANDofNumbersRange.py)|Medium|
|202.|[Happy Number](https://leetcode.com/problems/happy-number/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/HappyHumber.py)|Easy|
|203.|[Remove Linked List Elements](https://leetcode.com/problems/remove-linked-list-elements/)|[Python](/Easy/203.RemoveLinkedListElements.py)|Easy|`Linked List`|
|204.|[Count Primes](https://leetcode.com/problems/count-primes/)|[Python](/Easy/204.CountPrimes.py)|Easy|
|205.|[Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/)|[Python](/Easy/205.IsomorphicStrings.py)|Easy|`Dictionary`|
|206.|[Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)|[Python](/Easy/206.ReverseLinkedList.py)|Easy|`Linked List`, brute force|
|206.|[Reverse Linked List](https://leetcode.com/problems/reverse-linked-list/)|[Python](/Easy/206.ReverseLinkedList(rightappr).py)|Easy|`Linked List`|
|208.|[Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree/)|[Python](/Medium/208.ImplementTrie(PrefixTree).py)|Medium|`Trie`, 1st time all by myself|
|209.|[Minimum Size Subarray Sum](https://leetcode.com/problems/minimum-size-subarray-sum/)|[Python](/Medium/209.MinimumSizeSubarraySum.py)|Medium|
|211.|[Add and Search Word - Data structure design](https://leetcode.com/problems/add-and-search-word-data-structure-design/)|[Python](/Medium/211.AddandSearchWord-Datastructuredesign.py)|Medium|Need to resolve|
|215.|[Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/)|[Python](/Medium/215.KthLargestElementinanArray.py)|Medium|`sorted()`|
|216.|[Combination Sum III](https://leetcode.com/problems/combination-sum-iii/)|[Python](/Medium/216.CombinationSumIII.py)|Medium|`Backtracking`|
|217.|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)|[Python](/Easy/217.ContainsDuplicate(Dict).py)|Easy|`Dictionary`|
|219.|[Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)|[Python](/Easy/219.ContainsDuplicateII.py)|Easy|`Dictionary`, `enumerate`|
|220.|[Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii/)|[Python](/Medium/220.ContainsDuplicateIII.py)|Medium|`Two pointers`?|
|221.|[Maximal Square](https://leetcode.com/problems/maximal-square)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/MaximalSquare.py)|Medium|
|222.|[Count Complete Tree Nodes](https://leetcode.com/problems/count-complete-tree-nodes/)|[Python](/Medium/222.CountCompleteTreeNodes.py)|Medium|`Recursion`|
|225.|[Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues/)|[Python](/Easy/225.ImplementStackusingQueues.py)|Easy|`List`|
|226.|[Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/)|[Python](/Easy/226.InvertBinaryTree.py)|Easy|`Recursion`|
|227.|[Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii/)|[Python](/Medium/227.BasicCalculatorII.py)|Medium|`Queue`, Brute Force|
|228.|[Summary Ranges](https://leetcode.com/problems/summary-ranges/)|[Python](/Medium/228.SummaryRanges.py)|Medium|`Two Pointers`|
|229.|[Majority Element II](https://leetcode.com/problems/majority-element-ii/)|[Python](/Medium/229.MajorityElementII(BruteForce).py)|Medium|Brute Force|
|229.|[Majority Element II](https://leetcode.com/problems/majority-element-ii/)|[Python](/Medium/229.MajorityElementII.py)|Medium|a bit optimized|
|230.|[Kth Smallest Element in a BST](https://leetcode.com/problems/kth-smallest-element-in-a-bst/)|[Python](/Medium/230.KthSmallestElementinaBST.py)|Medium|`Recursion`, inorder, brute force|
|232.|[Implement Queue using Stacks](https://leetcode.com/problems/implement-queue-using-stacks/)|[Python](/Easy/232.ImplementQueueusingStacks.py)|Easy|`List`|
|234.|[Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/)|[Python](/Easy/234.PalindromeLinkedList.py)|Easy|`Linked List`|
|237.|[Delete Node in a Linked List](https://leetcode.com/problems/delete-node-in-a-linked-list/)|[Python](/Easy/237.DeleteNodeinaLinkedList.py)|Easy|`Linked List`|
|238.|[Product of Array Except Self](https://leetcode.com/problems/product-of-array-except-self/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/ProductofArrayExceptSelf.py)|Medium|
|240.|[Search a 2D Matrix II](https://leetcode.com/problems/search-a-2d-matrix-ii/)|[Python](/Medium/240.Searcha2DMatrixII.py)|Medium|`Binary Search`|
|242.|[Valid Anagram](https://leetcode.com/problems/valid-anagram/)|[Python](/Easy/242.ValidAnagram.py)|Easy|
|257.|[Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths/)|[Python](/Easy/257.BinaryTreePaths.py)|Easy|`Binary Tree` (preorder), `Recursion`|
|258.|[Add Digits](https://leetcode.com/problems/add-digits/)|[Python](/Easy/258.AddDigits.py)|Easy||
|260.|[Single Number III](https://leetcode.com/problems/single-number-iii/)|[Python](/Medium/260.SingleNumberIII.py)|Medium|`Set`|
|268.|[Missing Number](https://leetcode.com/problems/missing-number/)|[Python](/Easy/268.MissingNumber.py)|Easy|
|274.|[H-Index](https://leetcode.com/problems/h-index/)|[Python](/Medium/274.H-Index.py)|Medium|
|275.|[H-Index II](https://leetcode.com/problems/h-index-ii/)|[Python](/Medium/275.H-IndexII.py)|Medium|Solution for problem #274 worked fine|
|283.|[Move Zeroes](https://leetcode.com/problems/move-zeroes/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/MoveZeroes.py)|Easy|
|284.|[Peeking Iterator](https://leetcode.com/problems/peeking-iterator/)|[Python](/Medium/284.PeekingIterator.py)|Medium||
|289.|[Game of Life](https://leetcode.com/problems/game-of-life/)|[Python](/Medium/289.GameofLife.py)|Medium||
|290.|[Word Pattern](https://leetcode.com/problems/word-pattern/)|[Python](/Easy/290.WordPattern.py)|Easy|`Dictionary`, `enumerate`|
|295.|[Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream/)|[Python](/Hard/295.FindMedianfromDataStream(bruteforce).py)|Hard|Brute Force|
|295.|[Find Median from Data Stream](https://leetcode.com/problems/find-median-from-data-stream/)|[Python](/Hard/295.FindMedianfromDataStream(binarySearch).py)|Hard|`Binary Search`|
|297.|[Serialize and Deserialize Binary Tree](https://leetcode.com/problems/serialize-and-deserialize-binary-tree/)|[Python](/Hard/297.SerializeandDeserializeBinaryTree.py)|Hard|`BFS`|
|299.|[Bulls and Cows](https://leetcode.com/problems/bulls-and-cows/)|[Python](/Easy/299.BullsandCows.py)|Easy||
|304.|[Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable/)|[Python](/Medium/304.RangeSumQuery2D-Immutable(bruteforce).py)|Medium|Brute force|
|304.|[Range Sum Query 2D - Immutable](https://leetcode.com/problems/range-sum-query-2d-immutable/)|[Python](/Medium/304.RangeSumQuery2D-Immutable(bruteforce2).py)|Medium|A bit optimized but still brute force|
|307.|[Range Sum Query - Mutable](https://leetcode.com/problems/range-sum-query-mutable/)|[Python](/Medium/307.RangeSumQuery - Mutable.py)|Medium||
|318.|[Maximum Product of Word Lengths](https://leetcode.com/problems/maximum-product-of-word-lengths/)|[Python](/Medium/318.MaximumProductofWordLengths.py)|Medium|Brute Force|
|326.|[Power of Three](https://leetcode.com/problems/power-of-three/)|[Python](/Easy/326.PowerofThree.py)|Easy|`while`|
|328.|[Odd Even Linked List](https://leetcode.com/problems/odd-even-linked-list/)|[Python](/Medium/328.OddEvenLinkedList.py)|Medium|`Linked List`|
|329.|[Longest Increasing Path in a Matrix](https://leetcode.com/problems/longest-increasing-path-in-a-matrix/)|[Python](/Hard/329.LongestIncreasingPathinaMatrix.py)|Hard|`DFS`, `LRU_cache`, Brute Force|
|334.|[Increasing Triplet Subsequence](https://leetcode.com/problems/increasing-triplet-subsequence/)|[Python](Medium/334.IncreasingTripletSubsequence.py)|Medium|Brute Force|
|341.|[Flatten Nested List Iterator](https://leetcode.com/problems/flatten-nested-list-iterator/)|[Python](Medium/341.FlattenNestedListIterator.py)|Medium||
|342.|[Power of Four](https://leetcode.com/problems/power-of-four/)|[Python](/Easy/342.PowerofFour(BruteForce).py)|Easy|Brute Force|
|342.|[Power of Four](https://leetcode.com/problems/power-of-four/)|[Python](/Easy/342.PowerofFour.py)|Easy|`Bitwise`|
|344.|[Reverse String](https://leetcode.com/problems/reverse-string/)|[Python](/Easy/344.ReverseString.py)|Easy|
|345.|[Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string/)|[Python](/Easy/345.ReverseVowelsofaString(string).py)|Easy|`String`, in-place, slow|
|345.|[Reverse Vowels of a String](https://leetcode.com/problems/reverse-vowels-of-a-string/)|[Python](/Easy/345.ReverseVowelsofaString(list).py)|Easy|`List`, fast, ~x4|
|347.|[Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/)|[Python](/Medium/347.TopKFrequentElements.py)|Medium|`Hash Table`|
|355.|[Design Twitter](https://leetcode.com/problems/design-twitter/)|[Python](/Medium/355.DesignTwitter.py)|Medium|May be improved with `collections`|
|376.|[Wiggle Subsequence](https://leetcode.com/problems/wiggle-subsequence/)|[Python](/Medium/376.WiggleSubsequence.py)|Medium||
|378.|[Kth Smallest Element in a Sorted Matrix](https://leetcode.com/problems/kth-smallest-element-in-a-sorted-matrix/)|[Python](/Medium/378.KthSmallestElementinaSortedMatrix.py)|Medium|Converted `matrix` into `list`|
|380.|[Insert Delete GetRandom O(1)](https://leetcode.com/problems/insert-delete-getrandom-o1/)|[Python](/Medium/380.InsertDeleteGetRandomO(1).py)|Medium|not O(1), Brute force|
|381.|[Insert Delete GetRandom O(1) - Duplicates allowed](https://leetcode.com/problems/insert-delete-getrandom-o1-duplicates-allowed/)|[Python](/Hard/381.InsertDeleteGetRandomO(1)-Duplicatesallowed.py)|Hard|not O(1), Brute force|
|382.|[Linked List Random Node](https://leetcode.com/problems/linked-list-random-node/)|[Python](/Medium/382.LinkedListRandomNode.py)|Medium|`random.choice()`|
|384.|[Shuffle an Array](https://leetcode.com/problems/shuffle-an-array/)|[Python](/Medium/384.ShuffleanArray.py)|Medium|`random.sample()`|
|387.|[First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/)|[Python](/Easy/387.FirstUniqueCharacterinaString(BruteForce).py)|Easy|Brute Force|
|387.|[First Unique Character in a String](https://leetcode.com/problems/first-unique-character-in-a-string/)|[Python](/Easy/387.FirstUniqueCharacterinaString.py)|Easy|`Dictionary`, `enumerate`|
|389.|[Find the Difference](https://leetcode.com/problems/find-the-difference/)|[Python](/Easy/389.FindtheDifference(set).py)|Easy|`set`, `.count()`|
|389.|[Find the Difference](https://leetcode.com/problems/find-the-difference/)|[Python](/Easy/389.FindtheDifference.py)|Easy|`.replace()`|
|392.|[Is Subsequence](https://leetcode.com/problems/is-subsequence/)|[Python](/Easy/392.IsSubsequence.py)|Easy||
|394.|[Decode String](https://leetcode.com/problems/decode-string/)|[Python](/Medium/394.DecodeString.py)|Medium|`Stack`|
|395.|[Longest Substring with At Least K Repeating Characters](https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters/)|[Python](/Medium/395.LongestSubstringwithAtLeastKRepeatingCharacters.py)|Medium|`collections`, `Recursion`|
|398.|[Random Pick Index](https://leetcode.com/problems/random-pick-index/)|[Python](/Medium/398.RandomPickIndex.py)|Medium|`random.choice()`|
|399.|[Evaluate Division](https://leetcode.com/problems/evaluate-division/)|[Python](/Medium/399.EvaluateDivision.py)|Medium|God bless youtube|
|402.|[Remove K Digits](https://leetcode.com/problems/remove-k-digits/)|[Python](/Medium/402.RemoveKDigits.py)|Medium|`Stack`|
|404.|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/)|[Python](/Easy/404.SumofLeftLeaves.py)|Easy|`Recursion`, preorder|
|409.|[Longest Palindrome](https://leetcode.com/problems/longest-palindrome/)|[Python](/Easy/409.LongestPalindrome.py)|Easy||
|412.|[Fizz Buzz](https://leetcode.com/problems/fizz-buzz/)|[Python](/Easy/412.FizzBuzz.py)|Easy||
|421.|[Maximum XOR of Two Numbers in an Array](https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array/)|[Python](/Medium/421.MaximumXORofTwoNumbersinanArray.py)|Medium|googled soln|
|423.|[Reconstruct Original Digits from English](https://leetcode.com/problems/reconstruct-original-digits-from-english/)|[Python](/Medium/423.ReconstructOriginalDigitsfromEnglish.py)|Medium||
|429.|[N-ary Tree Level Order Traversal](https://leetcode.com/problems/n-ary-tree-level-order-traversal/)|[Python](/Medium/429.N-aryTreeLevelOrderTraversal.py)|Medium|`BFS`|
|432.|[All O\`one Data Structure](https://leetcode.com/problems/all-oone-data-structure/)|[Python](/Hard/432.AllOoneDataStructure.py)|Hard|`Dictionary` as Data Structure|
|435.|[Non-overlapping Intervals](https://leetcode.com/problems/non-overlapping-intervals/)|[Python](/Medium/435.Non-overlappingIntervals.py)|Medium|`lambda`|
|436.|[Find Right Interval](https://leetcode.com/problems/find-right-interval/)|[Python](/Medium/436.FindRightInterval.py)|Medium|Brute Force|
|437.|[Path Sum III](https://leetcode.com/problems/path-sum-iii/)|[Python](/Medium/437.PathSumIII.py)|Medium|`DFS`|
|441.|[Arranging Coins](https://leetcode.com/problems/arranging-coins/)|[Python](/Easy/441.ArrangingCoins.py)|Easy|Iteratively|
|442.|[Find All Duplicates in an Array](https://leetcode.com/problems/find-all-duplicates-in-an-array/)|[Python](/Medium/442.FindAllDuplicatesinanArray.py)|Medium|`set()`|
|445.|[Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii/)|[Python](/Medium/445.AddTwoNumbersII.py)|Medium|converted to `int` and back to `Linked List`|
|449.|[Serialize and Deserialize BST](https://leetcode.com/problems/serialize-and-deserialize-bst/)|[Python](/Medium/449.SerializeandDeserializeBST.py)|Medium|Complicated solution - resolve|
|450.|[Delete Node in a BST](https://leetcode.com/problems/delete-node-in-a-bst/)|[Python](/Medium/450.DeleteNodeinaBST.py)|Medium|`Binary Search Tree`, `Recursion`|
|451.|[Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency/)|[Python](/Medium/451.SortCharactersByFrequency.py)|Medium|Surprisingly fast solution|
|452.|[Minimum Number of Arrows to Burst Balloons](https://leetcode.com/problems/minimum-number-of-arrows-to-burst-balloons/)|[Python](/Medium/452.MinimumNumberofArrowstoBurstBalloons.py)|Medium||
|454.|[4Sum II](https://leetcode.com/problems/4sum-ii/)|[Python](/Medium/454.4SumII.py)|Medium|`Dictionary`|
|456.|[132 Pattern](https://leetcode.com/problems/132-pattern/)|[Python](/Medium/456.132Pattern.py)|Medium|Brute Force|
|458.|[Poor Pigs](https://leetcode.com/problems/poor-pigs/)|[Python](/Hard/458.PoorPigs.py)|Hard|`math`|
|459.|[Repeated Substring Pattern](https://leetcode.com/problems/repeated-substring-pattern/)|[Python](/Easy/459.RepeatedSubstringPattern.py)|Easy||
|462.|[Minimum Moves to Equal Array Elements II](https://leetcode.com/problems/minimum-moves-to-equal-array-elements-ii/)|[Python](/Medium/462.MinimumMovestoEqualArrayElementsII.py)|Medium|median|
|468.|[Validate IP Address](https://leetcode.com/problems/validate-ip-address/)|[Python](/Medium/468.ValidateIPAddress.py)|Medium||
|470.|[Implement Rand10() Using Rand7()](https://leetcode.com/problems/implement-rand10-using-rand7/)|[Python](/Medium/470.ImplementRand10()UsingRand7().py)|Medium|'Invented the wheel'|
|476.|[Number Complement](https://leetcode.com/problems/number-complement/)|[Python](/Easy/476.NumberComplement.py)|Easy||
|478.|[Generate Random Point in a Circle](https://leetcode.com/problems/generate-random-point-in-a-circle/)|[Python](/Medium/478.GenerateRandomPointinaCircle.py)|Medium||
|495.|[Teemo Attacking](https://leetcode.com/problems/teemo-attacking/)|[Python](/Medium/495.TeemoAttacking.py)|Medium||
|496.|[Next Greater Element I](https://leetcode.com/problems/next-greater-element-i/)|[Python](/Easy/496.NextGreaterElementI.py)|Easy|Brute force - resolve|
|497.|[Random Point in Non-overlapping Rectangles](https://leetcode.com/problems/random-point-in-non-overlapping-rectangles/)|[Python](/Medium/497.RandomPointinNon-overlappingRectangles.py)|Medium|`Random`, `Bisect`|
|498.|[Diagonal Traverse](https://leetcode.com/problems/diagonal-traverse/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Medium/498.DiagonalTraverse.py)|Medium|Used theory from GfG.com|
|500.|[Keyboard Row](https://leetcode.com/problems/keyboard-row/)|[Python](/Easy/500.KeyboardRow.py)|Easy|`Dictionary`|
|501.|[Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree/)|[Python](/Easy/501.FindModeinBinarySearchTree.py)|Easy|`Recursion`|
|503.|[Next Greater Element II](https://leetcode.com/problems/next-greater-element-ii/)|[Python](/Medium/503.NextGreaterElementII.py)|Medium|Brute Force|
|509.|[Fibonacci Number](https://leetcode.com/problems/fibonacci-number/)|[Python](/Easy/509.FibonacciNumber(list).py)|Easy|`List`|
|509.|[Fibonacci Number](https://leetcode.com/problems/fibonacci-number/)|[Python](/Easy/509.FibonacciNumber(Dict).py)|Easy|`Dictionary`|
|509.|[Fibonacci Number](https://leetcode.com/problems/fibonacci-number/)|[Python](/Easy/509.FibonacciNumber(TwoVar).py)|Easy|Used two variables n1 & n2|
|513.|[Find Bottom Left Tree Value](https://leetcode.com/problems/find-bottom-left-tree-value/)|[Python](/Medium/513.FindBottomLeftTreeValue.py)|Medium|`BFS`|
|515.|[Find Largest Value in Each Tree Row](https://leetcode.com/problems/find-largest-value-in-each-tree-row/)|[Python](/Medium/515.FindLargestValueinEachTreeRow.py)|Medium|`BFS`|
|520.|[Detect Capital](https://leetcode.com/problems/detect-capital/)|[Python](/Easy/520.DetectCapital.py)|Easy|Built-in functions|
|524.|[Longest Word in Dictionary through Deleting](https://leetcode.com/problems/longest-word-in-dictionary-through-deleting/)|[Python](/Medium/524.LongestWordinDictionarythroughDeleting.py)|Medium||
|525.|[Contiguous Array](https://leetcode.com/problems/contiguous-array/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/ContiguousArray.py)|Medium|
|526.|[Beautiful Arrangement](https://leetcode.com/problems/beautiful-arrangement/)|[Python](/Medium/526.BeautifulArrangement.py)|Medium|`DFS`, brute force|
|530.|[Minimum Absolute Difference in BST](https://leetcode.com/problems/minimum-absolute-difference-in-bst/)|[Python](/Easy/530.MinimumAbsoluteDifferenceinBST.py)|Easy|Bad solution - resolve|
|532.|[K-diff Pairs in an Array](https://leetcode.com/problems/k-diff-pairs-in-an-array/)|[Python](/Medium/532.K-diffPairsinanArray.py)|Medium|Brute force|
|535.|[Encode and Decode TinyURL](https://leetcode.com/problems/encode-and-decode-tinyurl/)|[Python](/Medium/535.EncodeandDecodeTinyURL.py)|Medium|`Dictionary` as db, `random` generated url|
|538.|[Convert BST to Greater Tree](https://leetcode.com/problems/convert-bst-to-greater-tree/)|[Python](/Easy/538.ConvertBSTtoGreaterTree.py)|Easy|`DFS`, recursion|
|540.|[Single Element in a Sorted Array](https://leetcode.com/problems/single-element-in-a-sorted-array/)|[Python](/Medium/540.SingleElementinaSortedArray.py)|Medium|`Binary Search`|
|543.|[Diameter of Binary Tree](https://leetcode.com/problems/diameter-of-binary-tree/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/DiameterofBinaryTree.py)|Easy|
|554.|[Brick Wall](https://leetcode.com/problems/brick-wall/)|[Python](/Medium/554.BrickWall.py)|Medium|`Hash Table`|
|556.|[Next Greater Element III](https://leetcode.com/problems/next-greater-element-iii/)|[Python](/Medium/556.NextGreaterElementIII.py)|Medium||
|559.|[Maximum Depth of N-ary Tree](https://leetcode.com/problems/maximum-depth-of-n-ary-tree/)|[Python](/Easy/559.MaximumDepthofN-aryTree.py)|Easy|`BFS`|
|560.|[Subarray Sum Equals K](https://leetcode.com/problems/subarray-sum-equals-k)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/SubarraySumEqualsK.py)|Medium|
|563.|[Binary Tree Tilt](https://leetcode.com/problems/binary-tree-tilt/)|[Python](/Easy/563.BinaryTreeTilt.py)|Easy|`Binary Tree`, `postorder`, overcode|
|566.|[Reshape the Matrix](https://leetcode.com/problems/reshape-the-matrix/)|[Python](/Easy/566.ReshapetheMatrix.py)|Easy|Brute Force|
|575.|[Distribute Candies](https://leetcode.com/problems/distribute-candies/)|[Python](/Easy/575.DistributeCandies.py)|Easy||
|581.|[Shortest Unsorted Continuous Subarray](https://leetcode.com/problems/shortest-unsorted-continuous-subarray/)|[Python](/Medium/581.ShortestUnsortedContinuousSubarray.py)|Medium||
|589.|[N-ary Tree Preorder Traversal](https://leetcode.com/problems/n-ary-tree-preorder-traversal/)|[Python](/Easy/589.N-aryTreePreorderTraversal.py)|Easy|`Recursion`|
|590.|[N-ary Tree Postorder Traversal](https://leetcode.com/problems/n-ary-tree-postorder-traversal/)|[Python](/Easy/590.N-aryTreePostorderTraversal.py)|Easy|`Recursion`|
|593.|[Valid Square](https://leetcode.com/problems/valid-square/)|[Python](/Medium/593.ValidSquare.py)|Medium||
|594.|[Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence/)|[Python](/Easy/594.LongestHarmoniousSubsequence(defaultdict).py)|Easy|defaultdict|
|594.|[Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence/)|[Python](/Easy/594.LongestHarmoniousSubsequence(Counter).py)|Easy|Counter|
|599.|[Minimum Index Sum of Two Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists/)|[Python](/Easy/599.MinimumIndexSumofTwoLists.py)|Easy|`Dictionary`, `enumerate`|
|605.|[Can Place Flowers](https://leetcode.com/problems/can-place-flowers/)|[Python](/Easy/605.CanPlaceFlowers.py)|Easy|simple counter|
|609.|[Find Duplicate File in System](https://leetcode.com/problems/find-duplicate-file-in-system/)|[Python](/Medium/609.FindDuplicateFileinSystem.py)|Medium|`Dictionary`, nested `for loop`, `list comprehension`|
|622.|[Design Circular Queue](https://leetcode.com/problems/design-circular-queue/)|[Python](/Medium/622.DesignCircularQueue.py)|Medium|Implement through `list` (first time)|
|623.|[Add One Row to Tree](https://leetcode.com/problems/add-one-row-to-tree/)|[Python](/Medium/623.AddOneRowtoTree.py)|Medium|`BFS`|
|637.|[Average of Levels in Binary Tree](https://leetcode.com/problems/average-of-levels-in-binary-tree/)|[Python](/Easy/637.AverageofLevelsinBinaryTree.py)|Easy|`Binary Tree`, `Recursion`|
|641.|[Design Circular Deque](https://leetcode.com/problems/design-circular-deque/)|[Python](/Medium/641.DesignCircularDeque.py)|Medium|Need to resolve without use of builtin functions (first time)|
|645.|[Set Mismatch](https://leetcode.com/problems/set-mismatch/)|[Python](/Easy/645.SetMismatch.py)|Easy|`collections.Counter`|
|647.|[Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings/)|[Python](/Medium/647.PalindromicSubstrings.py)|Medium||
|653.|[Two Sum IV - Input is a BST](https://leetcode.com/problems/two-sum-iv-input-is-a-bst/)|[Python](/Easy/653.TwoSumIV-InputisaBST.py)|Easy|Brute Force - resolve|
|654.|[Maximum Binary Tree](https://leetcode.com/problems/maximum-binary-tree/)|[Python](/Medium/654.MaximumBinaryTree.py)|Medium|`DFS`, `Recursion`|
|657.|[Robot Return to Origin](https://leetcode.com/problems/robot-return-to-origin/)|[Python](/Easy/657.RobotReturntoOrigin.py)|Easy|`Dictionary`|
|658.|[Find K Closest Elements](https://leetcode.com/problems/find-k-closest-elements/)|[Python](/Medium/658.FindKClosestElements.py)|Medium|`Binary Search`|
|665.|[Non-decreasing Array](https://leetcode.com/problems/non-decreasing-array/)|[Python](/Easy/665.Non-decreasingArray.py)|Easy|Brute Force|
|667.|[Beautiful Arrangement II](https://leetcode.com/problems/beautiful-arrangement-ii/)|[Python](/Medium/667.BeautifulArrangementII.py)|Medium||
|671.|[Second Minimum Node In a Binary Tree](https://leetcode.com/problems/second-minimum-node-in-a-binary-tree/)|[Python](/Easy/671.SecondMinimumNodeInaBinaryTree.py)|Easy|`DFS`, `Recursion`|
|674.|[Longest Continuous Increasing Subsequence](https://leetcode.com/problems/longest-continuous-increasing-subsequence/)|[Python](/Easy/674.LongestContinuousIncreasingSubsequence.py)|Easy|simple counter|
|677.|[Map Sum Pairs](https://leetcode.com/problems/map-sum-pairs/)|[Python](/Medium/677.MapSumPairs.py)|Medium|`Trie`|
|678.|[Valid Parenthesis String](https://leetcode.com/problems/valid-parenthesis-string/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/ValidParenthesisString.py)|Medium|
|682.|[Baseball Game](https://leetcode.com/problems/baseball-game/)|[Python](/Easy/682.BaseballGame.py)|Easy||
|690.|[Employee Importance](https://leetcode.com/problems/employee-importance/)|[Python](/Easy/690.EmployeeImportance.py)|Easy|`BFS`|
|695.|[Max Area of Island](https://leetcode.com/problems/max-area-of-island/)|[Python](/Medium/695.MaxAreaofIsland.py)|Medium|`DFS`|
|696.|[Count Binary Substrings](https://leetcode.com/problems/count-binary-substrings/)|[Python](/Easy/696.CountBinarySubstrings.py)|Easy|
|700.|[Search in a Binary Search Tree](https://leetcode.com/problems/search-in-a-binary-search-tree/)|[Python](/Easy/700.SearchinaBinarySearchTree.py)|Easy|`Binary Search Tree`, `Recursion`|
|701.|[Insert into a Binary Search Tree](https://leetcode.com/problems/insert-into-a-binary-search-tree/)|[Python](/Medium/701.InsertintoaBinarySearchTree.py)|Medium|`Binary Search Tree`, `Recursion`|
|703.|[Kth Largest Element in a Stream](https://leetcode.com/problems/kth-largest-element-in-a-stream/)|[Python](/Easy/703.KthLargestElementinaStream.py)|Easy|brute force|
|705.|[Design HashSet](https://leetcode.com/problems/design-hashset/)|[Python](/Easy/705.DesignHashSet.py)|Easy|`list` as a set|
|706.|[Design HashMap](https://leetcode.com/problems/design-hashmap/)|[Python](/Easy/706.DesignHashMap.py)|Easy|`list`|
|707.|[Design Linked List](https://leetcode.com/problems/design-linked-list/)|[Python](/Medium/707.DesignLinkedList.py)|Medium|`Linked List`, first time|
|709.|[To Lower Case](https://leetcode.com/problems/to-lower-case/)|[Python](/Easy/709.ToLowerCase.py)|Easy|Two solutions. 1st w. in place changes, 2nd saves in var|
|713.|[Subarray Product Less Than K](https://leetcode.com/problems/subarray-product-less-than-k/)|[Python](/Medium/713.SubarrayProductLessThanK.py)|Medium|`Two pointers`|
|720.|[Longest Word in Dictionary](https://leetcode.com/problems/longest-word-in-dictionary/)|[Python](/Easy/720.LongestWordinDictionary.py)|Easy|`Trie`|
|722.|[Remove Comments](https://leetcode.com/problems/remove-comments/)|[Python](/Medium/722.RemoveComments.py)|Medium|`String`|
|728.|[Self Dividing Numbers](https://leetcode.com/problems/self-dividing-numbers/)|[Python](/Easy/728.SelfDividingNumbers.py)|Easy|Math|
|729.|[My Calendar I](https://leetcode.com/problems/my-calendar-i/)|[Python](/Medium/729.MyCalendarI.py)|Medium|`Limked List`, `Dictionary`|
|735.|[Asteroid Collision](https://leetcode.com/problems/asteroid-collision/)|[Python](/Medium/735.AsteroidCollision.py)|Medium|`Stack`|
|744.|[Find Smallest Letter Greater Than Target](https://leetcode.com/problems/find-smallest-letter-greater-than-target/)|[Python](/Easy/744.FindSmallestLetterGreaterThanTarget.py)|Easy|`Binary Search`|
|746.|[Min Cost Climbing Stairs](https://leetcode.com/problems/min-cost-climbing-stairs/)|[Python](/Easy/746.MinCostClimbingStairs.py)|Easy|`DP`|
|754.|[Reach a Number](https://leetcode.com/problems/reach-a-number/)|[Python](/Medium/754.ReachaNumber.py)|Medium|Math|
|763.|[Partition Labels](https://leetcode.com/problems/partition-labels/)|[Python](/Medium/763.PartitionLabels(bruteforce).py)|Medium|Brute Force - resolve|
|771.|[Jewels and Stones](https://leetcode.com/problems/jewels-and-stones/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/771.JewelsandStones.py)|Easy|`while loop`, `for loop` and `list comprehension`|
|775.|[Global and Local Inversions](https://leetcode.com/problems/global-and-local-inversions/)|[Python](/Medium/775.GlobalandLocalInversions.py)|Medium||
|785.|[Is Graph Bipartite?](https://leetcode.com/problems/is-graph-bipartite/)|[Python](/Medium/785.IsGraphBipartite.py)|Medium|Iteratively `BFS`, `stack`, `XOR`|
|791.|[Custom Sort String](https://leetcode.com/problems/custom-sort-string/)|[Python](/Medium/791.CustomSortString.py)|Medium||
|804.|[Unique Morse Code Words](https://leetcode.com/problems/unique-morse-code-words/)|[Python](/Easy/804.UniqueMorseCodeWords.py)|Easy|`Dictionary`|
|807.|[Max Increase to Keep City Skyline](https://leetcode.com/problems/max-increase-to-keep-city-skyline/)|[Python](/Medium/807.MaxIncreasetoKeepCitySkyline.py)|Medium||
|811.|[Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count/)|[Python](/Easy/811.SubdomainVisitCount.py)|Easy|`Dictionary`|
|817.|[Linked List Components](https://leetcode.com/problems/linked-list-components/)|[Python](/Medium/817.LinkedListComponents(set).py)|Medium|`Set`|
|817.|[Linked List Components](https://leetcode.com/problems/linked-list-components/)|[Python](/Medium/817.LinkedListComponents.py)|Medium|`List`, 35 times slower|
|820.|[Short Encoding of Words](https://leetcode.com/problems/short-encoding-of-words/)|[Python](/Medium/820.ShortEncodingofWords.py)|Medium|Brute Force|
|821.|[Shortest Distance to a Character](https://leetcode.com/problems/shortest-distance-to-a-character/)|[Python](/Easy/821.ShortestDistancetoaCharacter.py)|Easy|overcode|
|824.|[Goat Latin](https://leetcode.com/problems/goat-latin/)|[Python](/Easy/824.GoatLatin.py)|Easy||
|832.|[Flipping an Image](https://leetcode.com/problems/flipping-an-image/)|[Python](/Easy/832.FlippinganImage.py)|Easy||
|832.|[Flipping an Image](https://leetcode.com/problems/flipping-an-image/)|[Python](/Easy/832.FlippinganImage(reverse).py)|Easy|`.reverse()`|
|835.|[Image Overlap](https://leetcode.com/problems/image-overlap/)|[Python](/Medium/835.ImageOverlap.py)|Medium|Brute Force|
|841.|[Keys and Rooms](https://leetcode.com/problems/keys-and-rooms/)|[Python](/Medium/841.KeysandRooms.py)|Medium|`BFS`|
|844.|[Backspace String Compare](https://leetcode.com/problems/backspace-string-compare/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/BackspaceStringCompare.py)|Easy|
|845.|[Longest Mountain in Array](https://leetcode.com/problems/longest-mountain-in-array/)|[Python](/Medium/845.LongestMountaininArray.py)|Medium|one pass|
|849.|[Maximize Distance to Closest Person](https://leetcode.com/problems/maximize-distance-to-closest-person/)|[Python](/Medium/849.MaximizeDistancetoClosestPerson.py)|Medium|
|852.|[Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/)|[Python](/Easy/852.PeakIndexinaMountainArray(ListComprehension).py)|Easy|`List comprehension`|
|852.|[Peak Index in a Mountain Array](https://leetcode.com/problems/peak-index-in-a-mountain-array/)|[Python](/Easy/852.PeakIndexinaMountainArray(set).py)|Easy|`Set`|
|858.|[Mirror Reflection](https://leetcode.com/problems/mirror-reflection/)|[Python](/Medium/858.MirrorReflection.py)|Medium||
|859.|[Buddy Strings](https://leetcode.com/problems/buddy-strings/)|[Python](/Easy/859.BuddyStrings.py)|Easy|Brute Force|
|865.|[Smallest Subtree with all the Deepest Nodes](https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/)|[Python](/Medium/865.SmallestSubtreewithalltheDeepestNodes.py)|Medium|`DFS`, `Recursion`|
|869.|[Reordered Power of 2](https://leetcode.com/problems/reordered-power-of-2/)|[Python](/Medium/869.ReorderedPowerof2.py)|Medium|`int` to `string`|
|872.|[Leaf-Similar Trees](https://leetcode.com/problems/leaf-similar-trees/)|[Python](/Easy/872.Leaf-SimilarTrees.py)|Easy|`Recursion`|
|876.|[Middle of the Linked List](https://leetcode.com/problems/middle-of-the-linked-list/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/MiddleoftheLinkedList.py)|Easy|
|880.|[Decoded String at Index](https://leetcode.com/problems/decoded-string-at-index/)|[Python](/Medium/880.DecodedStringatIndex.py)|Medium|
|881.|[Boats to Save People](https://leetcode.com/problems/boats-to-save-people/)|[Python](/Medium/881.BoatstoSavePeople.py)|Medium|`Two Pointers`|
|884.|[Uncommon Words from Two Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences/)|[Python](/Easy/884.UncommonWordsfromTwoSentences.py)|Easy|simple counter|
|890.|[Find and Replace Pattern](https://leetcode.com/problems/find-and-replace-pattern/)|[Python](/Medium/890.FindandReplacePattern.py)|Medium|`Dictionary`|
|895.|[Maximum Frequency Stack](https://leetcode.com/problems/maximum-frequency-stack/)|[Python](/Hard/895.MaximumFrequencyStack.py)|Hard||
|896.|[Monotonic Array](https://leetcode.com/problems/monotonic-array/)|[Python](/Easy/896.MonotonicArray.py)|Easy||
|897.|[Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree/)|[Python](/Easy/897.IncreasingOrderSearchTree.py)|Easy|`DFS`, iteratively|
|900.|[RLE Iterator](https://leetcode.com/problems/rle-iterator/)|[Python](/Medium/900.RLEIterator.py)|Medium||
|905.|[Sort Array By Parity](https://leetcode.com/problems/sort-array-by-parity/)|[Python](/Easy/905.SortArrayByParity.py)|Easy|`List`|
|908.|[Smallest Range I](https://leetcode.com/problems/smallest-range-i/)|[Python](/Easy/908.SmallestRangeI.py)|Easy||
|910.|[Smallest Range II](https://leetcode.com/problems/smallest-range-ii/)|[Python](/Medium/910.SmallestRangeII.py)|Medium||
|911.|[Online Election](https://leetcode.com/problems/online-election/)|[Python](/Medium/911.OnlineElection.py)|Medium|`Binary Search`|
|912.|[Sort an Array](https://leetcode.com/problems/sort-an-array/)|[Python](/Medium/912.SortanArray.py)|Medium|`sorted()`|
|916.|[Word Subsets](https://leetcode.com/problems/word-subsets/)|[Python](/Medium/916.WordSubsets.py)|Medium|`collections.Counter`, `Dictionary`|
|922.|[Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/)|[Python](/Easy/922.SortArrayByParityII(Dictionary).py)|Easy|`Dictionary`|
|922.|[Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/)|[Python](/Easy/922.SortArrayByParityII(List).py)|Easy|`List`|
|922.|[Sort Array By Parity II](https://leetcode.com/problems/sort-array-by-parity-ii/)|[Python](/Easy/922.SortArrayByParityII(TwoPointers).py)|Easy|`Two Pointers`|
|923.|[3Sum With Multiplicity](https://leetcode.com/problems/3sum-with-multiplicity/)|[Python](/Medium/923.3SumWithMultiplicity.py)|Medium|`collections.Counter`|
|929.|[Unique Email Addresses](https://leetcode.com/problems/unique-email-addresses/)|[Python](/Easy/929.UniqueEmailAddresses.py)|Easy|
|933.|[Number of Recent Calls](https://leetcode.com/problems/number-of-recent-calls/)|[Python](/Easy/933.NumberofRecentCalls(BinarySearch).py)|Easy|`Binary Search` and rewrite `list`|
|933.|[Number of Recent Calls](https://leetcode.com/problems/number-of-recent-calls/)|[Python](/Easy/933.NumberofRecentCalls(while).py)|Easy|`while` and rewrite `list`|
|933.|[Number of Recent Calls](https://leetcode.com/problems/number-of-recent-calls/)|[Python](/Easy/933.NumberofRecentCalls(whilePop).py)|Easy|`while` and `.pop()`|
|938.|[Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/)|[Python](/Easy/938.RangeSumofBST.py)|Easy|`Binary Search Tree`|
|938.|[Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/)|[Python](/Easy/938.RangeSumofBST(Optimized).py)|Easy|`Binary Search Tree`, Optimized solution|
|941.|[Valid Mountain Array](https://leetcode.com/problems/valid-mountain-array/)|[Python](/Easy/941.ValidMountainArray.py)|Easy||
|946.|[Validate Stack Sequences](https://leetcode.com/problems/validate-stack-sequences/)|[Python](/Medium/946.ValidateStackSequences.py)|Medium|`Stack`|
|949.|[Largest Time for Given Digits](https://leetcode.com/problems/largest-time-for-given-digits/)|[Python](/Easy/949.LargestTimeforGivenDigits.py)|Easy|`Itertools`|
|952.|[Largest Component Size by Common Factor](https://leetcode.com/problems/largest-component-size-by-common-factor/)|[Python](/Hard/952.LargestComponentSizebyCommonFactor.py)|Hard|Googled soln|
|953.|[Verifying an Alien Dictionary](https://leetcode.com/problems/verifying-an-alien-dictionary/)|[Python](/Easy/953.VerifyinganAlienDictionary.py)|Easy||
|961.|[N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array/)|[Python](/Easy/961.N-RepeatedElementinSize2NArray(BruteForce).py)|Easy|Brute Force|
|961.|[N-Repeated Element in Size 2N Array](https://leetcode.com/problems/n-repeated-element-in-size-2n-array/)|[Python](/Easy/961.N-RepeatedElementinSize2NArray.py)|Easy|`Dictionary`, a bit optimized|
|965.|[Univalued Binary Tree](https://leetcode.com/problems/univalued-binary-tree/)|[Python](/Easy/965.UnivaluedBinaryTree.py)|Easy|`Binary Tree`, `Recursion`|
|966.|[Vowel Spellchecker](https://leetcode.com/problems/vowel-spellchecker/)|[Python](/Medium/966.VowelSpellchecker.py)|Medium|`Dictionary`|
|967.|[Numbers With Same Consecutive Differences](https://leetcode.com/problems/numbers-with-same-consecutive-differences/)|[Python](/Medium/967.NumbersWithSameConsecutiveDifferences.py)|Medium|`DFS`|
|969.|[Pancake Sorting](https://leetcode.com/problems/pancake-sorting/)|[Python](/Medium/969.PancakeSorting.py)|Medium|sort|
|970.|[Powerful Integers](https://leetcode.com/problems/powerful-integers/)|[Python](/Easy/970.PowerfulIntegers.py)|Medium|nested `for` loops|
|977.|[Squares of a Sorted Array](https://leetcode.com/problems/squares-of-a-sorted-array/)|[Python](/Easy/977.SquaresofaSortedArray.py)|Easy|
|980.|[Unique Paths III](https://leetcode.com/problems/unique-paths-iii/)|[Python](/Hard/980.UniquePathsIII.py)|Hard|"googled soln", optimised|
|981.|[Time Based Key-Value Store](https://leetcode.com/problems/time-based-key-value-store/)|[Python](/Medium/981.TimeBasedKey-ValueStore.py)|Medium|`Binary Search`|
|983.|[Minimum Cost For Tickets](https://leetcode.com/problems/minimum-cost-for-tickets/)|[Python](https://github.com/YuriSpiridonov/August-LeetCoding-Challenge-2020/blob/master/Week%204/983.MinimumCostForTickets.py)|Medium|Googled soln|
|987.|[Vertical Order Traversal of a Binary Tree](https://leetcode.com/problems/vertical-order-traversal-of-a-binary-tree/)|[Python](/Medium/987.VerticalOrderTraversalofaBinaryTree.py)|Medium|`DFS`|
|989.|[Add to Array-Form of Integer](https://leetcode.com/problems/add-to-array-form-of-integer/)|[Python](/Easy/989.AddtoArray-FormofInteger.py)|Easy|`list`->`int`->`list`|
|991.|[Broken Calculator](https://leetcode.com/problems/broken-calculator/)|[Python](/Medium/991.BrokenCalculator.py)|Medium|`BFS`|
|993.|[Cousins in Binary Tree](https://leetcode.com/problems/cousins-in-binary-tree/)|[Python](/Easy/993.CousinsinBinaryTree.py)|Easy|`BFS`, iteratively|
|994.|[Rotting Oranges](https://leetcode.com/problems/rotting-oranges/)|[Python](/Medium/994.RottingOranges.py)|Medium|`DFS`|
|999.|[Available Captures for Rook](https://leetcode.com/problems/available-captures-for-rook/)|[Python](/Easy/999.AvailableCapturesforRook.py)|Easy||
|1002.|[Find Common Characters](https://leetcode.com/problems/find-common-characters/)|[Python](/Easy/1002.FindCommonCharacters.py)|Easy|`Dictionary`|
|1009.|[Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer/)|[Python](/Easy/1009.ComplementofBase10Integer.py)|Easy||
|1010.|[Pairs of Songs With Total Durations Divisible by 60](https://leetcode.com/problems/pairs-of-songs-with-total-durations-divisible-by-60/)|[Python](/Medium/1010.PairsofSongsWithTotalDurationsDivisibleby60.py)|Medium||
|1015.|[Smallest Integer Divisible by K](https://leetcode.com/problems/smallest-integer-divisible-by-k/)|[Python](/Medium/1015.SmallestIntegerDivisiblebyK.py)|Medium|counting lenght, Brute Force|
|1019.|[Next Greater Node In Linked List](https://leetcode.com/problems/next-greater-node-in-linked-list/)|[Python](/Medium/1019.NextGreaterNodeInLinkedList.py)|Medium||
|1021.|[Remove Outermost Parentheses](https://leetcode.com/problems/remove-outermost-parentheses/)|[Python](/Easy/1021.RemoveOutermostParentheses.py)|Easy|Overcode|
|1022.|[Sum of Root To Leaf Binary Numbers](https://leetcode.com/problems/sum-of-root-to-leaf-binary-numbers/)|[Python](/Easy/1022.SumofRootToLeafBinaryNumbers.py)|Easy|`DFS`, `Recursion`|
|1025.|[Divisor Game](https://leetcode.com/problems/divisor-game/)|[Python](/Easy/1025.DivisorGame.py)|Easy||
|1026.|[Maximum Difference Between Node and Ancestor](https://leetcode.com/problems/maximum-difference-between-node-and-ancestor/)|[Python](/Medium/1026.MaximumDifferenceBetweenNodeandAncestor.py)|Medium|`BFS`, iteratively|
|1032.|[Stream of Characters](https://leetcode.com/problems/stream-of-characters/)|[Python](/Hard/1032.StreamofCharacters.py)|Hard|`Trie`|
|1038.|[Binary Search Tree to Greater Sum Tree](https://leetcode.com/problems/binary-search-tree-to-greater-sum-tree/)|[Python](/Medium/1038.BinarySearchTreetoGreaterSumTree.py)|Medium|`DFS`, `recursion`|
|1041.|[Robot Bounded In Circle](https://leetcode.com/problems/robot-bounded-in-circle/)|[Python](/Medium/1041.RobotBoundedInCircle.py)|Medium|`Dictionary`|
|1046.|[Last Stone Weight](https://leetcode.com/problems/last-stone-weight/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/LastStoneWeight.py)|Easy|
|1047.|[Remove All Adjacent Duplicates In String](https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string/)|[Python](/Easy/1047.RemoveAllAdjacentDuplicatesInString.py)|Easy|Brute force - resolve|
|1079.|[Letter Tile Possibilities](https://leetcode.com/problems/letter-tile-possibilities/)|[Python](/Medium/1079.LetterTilePossibilities.py)|Medium|`itertools, permutations`|
|1091.|[Shortest Path in Binary Matrix](https://leetcode.com/problems/shortest-path-in-binary-matrix/)|[Python](/Medium/1091.ShortestPathinBinaryMatrix.py)|Medium|`BFS`, grid/matrix|
|1094.|[Car Pooling](https://leetcode.com/problems/car-pooling/)|[Python](/Medium/1094.CarPooling.py)|Medium||
|1095.|[Find in Mountain Array](https://leetcode.com/problems/find-in-mountain-array/)|[Python](/Hard/1095.FindinMountainArray.py)|Hard|`Binary Search`|
|1103.|[Distribute Candies to People](https://leetcode.com/problems/distribute-candies-to-people/)|[Python](/Easy/1103.DistributeCandiestoPeople.py)|Easy||
|1108.|[Defanging an IP Address](https://leetcode.com/problems/defanging-an-ip-address/)|[Python](/Easy/1108.DefanginganIPAddress(replace).py)|Easy|`.replace()`|
|1108.|[Defanging an IP Address](https://leetcode.com/problems/defanging-an-ip-address/)|[Python](/Easy/1108.DefanginganIPAddress(re.sub).py)|Easy|`re.sub`|
|1108.|[Defanging an IP Address](https://leetcode.com/problems/defanging-an-ip-address/)|[Python](/Easy/1108.DefanginganIPAddress(join).py)|Easy|`.join()`|
|1122.|[Relative Sort Array](https://leetcode.com/problems/relative-sort-array/)|[Python](/Easy/1122.RelativeSortArray.py)|Easy||
|1123.|[Lowest Common Ancestor of Deepest Leaves](https://leetcode.com/problems/lowest-common-ancestor-of-deepest-leaves/)|[Python](/Medium/1123.LowestCommonAncestorofDeepestLeaves.py)|Medium|`DFS`, `recursion`|
|1143.|[Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/LongestCommonSubsequenceSolution2DArray.py)|Medium|`2D Array`|
|1143.|[Longest Common Subsequence](https://leetcode.com/problems/longest-common-subsequence)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/LongestCommonSubsequence_recursion.py)|Medium|`Recursion`, Time Limit Exceeded|
|1160.|[Find Words That Can Be Formed by Characters](https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/)|[Python](/Easy/1160.FindWordsThatCanBeFormedbyCharacters.py)|Easy|`Dictionary`|
|1161.|[Maximum Level Sum of a Binary Tree](https://leetcode.com/problems/maximum-level-sum-of-a-binary-tree/)|[Python](/Medium/1161.MaximumLevelSumofaBinaryTree.py)|Medium|`BFS`|
|1169.|[Invalid Transactions](https://leetcode.com/problems/invalid-transactions/)|[Python](/Medium/1169.InvalidTransactions.py)|Medium|Ugly brute force|
|1171.|[Remove Zero Sum Consecutive Nodes from Linked List](https://leetcode.com/problems/remove-zero-sum-consecutive-nodes-from-linked-list/)|[Python](/Medium/1171.RemoveZeroSumConsecutiveNodesfromLinkedList.py)|Medium|Brute Force - resolve|
|1189.|[Maximum Number of Balloons](https://leetcode.com/problems/maximum-number-of-balloons/)|[Python](/Easy/1189.MaximumNumberofBalloons.py)|Easy|simple counter|
|1200.|[Minimum Absolute Difference](https://leetcode.com/problems/minimum-absolute-difference/)|[Python](/Easy/1200.MinimumAbsoluteDifference.py)|Easy|`Dictionary`|
|1207.|[Unique Number of Occurrences](https://leetcode.com/problems/unique-number-of-occurrences/)|[Python](/Easy/1207.UniqueNumberofOccurrences.py)|Easy|`Dictionary`|
|1217.|[Minimum Cost to Move Chips to The Same Position](https://leetcode.com/problems/minimum-cost-to-move-chips-to-the-same-position/)|[Python](/Easy/1217.MinimumCosttoMoveChipstoTheSamePosition.py)|Easy|simple counter|
|1221.|[Split a String in Balanced Strings](https://leetcode.com/problems/split-a-string-in-balanced-strings/)|[Python](/Easy/1221.SplitaStringinBalancedStrings.py)|Easy|`Stack`|
|1227.|[Airplane Seat Assignment Probability](https://leetcode.com/problems/airplane-seat-assignment-probability/)|[Python](/Medium/1227.AirplaneSeatAssignmentProbability.py)|Medium||
|1237.|[Find Positive Integer Solution for a Given Equation](https://leetcode.com/problems/find-positive-integer-solution-for-a-given-equation/)|[Python](/Easy/1237.FindPositiveIntegerSolutionforaGivenEquation.py)|Easy|`Binary Search`|
|1252.|[Cells with Odd Values in a Matrix](https://leetcode.com/problems/cells-with-odd-values-in-a-matrix/)|[Python](/Easy/1252.CellswithOddValuesinaMatrix.py)|Easy||
|1260.|[Shift 2D Grid](https://leetcode.com/problems/shift-2d-grid/)|[Python](/Easy/1260.Shift2DGrid.py)|Easy|`array`|
|1261.|[Find Elements in a Contaminated Binary Tree](https://leetcode.com/problems/find-elements-in-a-contaminated-binary-tree/)|[Python](/Medium/1261.FindElementsinaContaminatedBinaryTree.py)|Medium|`DFS`, iteratively|
|1266.|[Minimum Time Visiting All Points](https://leetcode.com/problems/minimum-time-visiting-all-points/)|[Python](/Easy/1266.MinimumTimeVisitingAllPoints.py)|Easy|simple counter|
|1268.|[Search Suggestions System](https://leetcode.com/problems/search-suggestions-system/)|[Python](/Medium/1268.SearchSuggestionsSystem.py)|Medium|Brute Force|
|1282.|[Group the People Given the Group Size They Belong To](https://leetcode.com/problems/group-the-people-given-the-group-size-they-belong-to/)|[Python](/Medium/1282.GroupthePeopleGiventheGroupSizeTheyBelongTo.py)|Medium||
|1283.|[Find the Smallest Divisor Given a Threshold](https://leetcode.com/problems/find-the-smallest-divisor-given-a-threshold/)|[Python](/Medium/1283.FindtheSmallestDivisorGivenaThreshold.py)|Medium|`Binary Search`|
|1286.|[Iterator for Combination](https://leetcode.com/problems/iterator-for-combination/)|[Python](/Medium/1286.IteratorforCombination.py)|Medium|`Itertools`|
|1287.|[Element Appearing More Than 25% In Sorted Array](https://leetcode.com/problems/element-appearing-more-than-25-in-sorted-array/)|[Python](/Easy/1287.ElementAppearingMoreThan25InSortedArray(for).py)|Easy|`for` loop|
|1287.|[Element Appearing More Than 25% In Sorted Array](https://leetcode.com/problems/element-appearing-more-than-25-in-sorted-array/)|[Python](/Easy/1287.ElementAppearingMoreThan25InSortedArray(binarySearch).py)|Easy|`Binary Search`|
|1288.|[Remove Covered Intervals](https://leetcode.com/problems/remove-covered-intervals/)|[Python](/Medium/1288.RemoveCoveredIntervals.py)|Medium|Brute force|
|1290.|[Convert Binary Number in a Linked List to Integer](https://leetcode.com/problems/convert-binary-number-in-a-linked-list-to-integer/)|[Python](/Easy/1290.ConvertBinaryNumberinaLinkedListtoInteger.py)|Easy||
|1291.|[Sequential Digits](https://leetcode.com/problems/sequential-digits/)|[Python](/Medium/1291.SequentialDigits.py)|Medium|`String`, can be solved with `int`|
|1299.|[Replace Elements with Greatest Element on Right Side](https://leetcode.com/problems/replace-elements-with-greatest-element-on-right-side/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/1299.ReplaceElementswithGreatestElementonRightSide.py)|Easy||
|1302.|[Deepest Leaves Sum](https://leetcode.com/problems/deepest-leaves-sum/)|[Python](/Medium/1302.DeepestLeavesSum.py)|Medium|`DFS`|
|1304.|[Find N Unique Integers Sum up to Zero](https://leetcode.com/problems/find-n-unique-integers-sum-up-to-zero/)|[Python](/Easy/1304.FindNUniqueIntegersSumuptoZero.py)|Easy||
|1305.|[All Elements in Two Binary Search Trees](https://leetcode.com/problems/all-elements-in-two-binary-search-trees/)|[Python](/Medium/1305.AllElementsinTwoBinarySearchTrees.py)|Medium|`BFS`, iteratively|
|1306.|[Jump Game III](https://leetcode.com/problems/jump-game-iii/)|[Python](/Medium/1306.JumpGameIII.py)|Medium|`BFS`, iteratively|
|1309.|[Decrypt String from Alphabet to Integer Mapping](https://leetcode.com/problems/decrypt-string-from-alphabet-to-integer-mapping/)|[Python](/Easy/1309.DecryptStringfromAlphabettoIntegerMapping.py)|Easy||
|1311.|[Get Watched Videos by Your Friends](https://leetcode.com/problems/get-watched-videos-by-your-friends/)|[Python](/Medium/1311.GetWatchedVideosbyYourFriends.py)|Medium|`BFS`, iteratively|
|1313.|[Decompress Run-Length Encoded List](https://leetcode.com/problems/decompress-run-length-encoded-list/)|[Python](/Easy/1313.DecompressRun-LengthEncodedList.py)|Easy||
|1315.|[Sum of Nodes with Even-Valued Grandparent](https://leetcode.com/problems/sum-of-nodes-with-even-valued-grandparent/)|[Python](/Medium/1315.SumofNodeswithEven-ValuedGrandparent.py)|Medium|`DFS`, `recursion`|
|1323.|[Maximum 69 Number](https://leetcode.com/problems/maximum-69-number/)|[Python](/Easy/1323.Maximum69Number.py)|Easy||
|1325.|[Delete Leaves With a Given Value](https://leetcode.com/problems/delete-leaves-with-a-given-value/)|[Python](/Medium/1325.DeleteLeavesWithaGivenValue.py)|Medium|`DFS`, `recursion`|
|1329.|[Sort the Matrix Diagonally](https://leetcode.com/problems/sort-the-matrix-diagonally/)|[Python](/Medium/1329.SorttheMatrixDiagonally.py)|Medium|`List`|
|1331.|[Rank Transform of an Array](https://leetcode.com/problems/rank-transform-of-an-array/)|[Python](/Easy/1331.RankTransformofanArray.py)|Easy|`Enumerate`|
|1332.|[Remove Palindromic Subsequences](https://leetcode.com/problems/remove-palindromic-subsequences/)|[Python](/Easy/1332.RemovePalindromicSubsequences.py)|Easy|Bad problem question|
|1337.|[The K Weakest Rows in a Matrix](https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/)|[Python](/Easy/1337.TheKWeakestRowsinaMatrix.py)|Easy||
|1338.|[Reduce Array Size to The Half](https://leetcode.com/problems/reduce-array-size-to-the-half/)|[Python](/Medium/1338.ReduceArraySizetoTheHalf.py)|Medium|`Dictionary`, `Enumerate`|
|1342.|[Number of Steps to Reduce a Number to Zero](https://leetcode.com/problems/number-of-steps-to-reduce-a-number-to-zero/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/1342.NumberofStepstoReduceaNumbertoZero.py)|Easy|`while loop`|
|1345.|[Jump Game IV](https://leetcode.com/problems/jump-game-iv/)|[Python](/Hard/1345.JumpGameIV.py)|Hard|`BFS`, iteratively|
|1347.|[Minimum Number of Steps to Make Two Strings Anagram](https://leetcode.com/problems/minimum-number-of-steps-to-make-two-strings-anagram/)|[Python](/Medium/1347.MinimumNumberofStepstoMakeTwoStringsAnagram.py)|Medium||
|1348.|[Tweet Counts Per Frequency](https://leetcode.com/problems/tweet-counts-per-frequency/)|[Python](/Medium/1348.TweetCountsPerFrequency.py)|Medium|Too slow, need to resolve it|
|1351.|[Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/)|[Python](/Easy/1351.CountNegativeNumbersinaSortedMatrix(binarySearch).py)|Easy|`Binary Search`|
|1351.|[Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/)|[Python](/Easy/1351.CountNegativeNumbersinaSortedMatrix(nestedFor).py)|Easy|nested `for loop`|
|1351.|[Count Negative Numbers in a Sorted Matrix](https://leetcode.com/problems/count-negative-numbers-in-a-sorted-matrix/)|[Python](/Easy/1351.CountNegativeNumbersinaSortedMatrix(nestedForOptimized).py)|Easy|nested `for loop` with a `break`|
|1352.|[Product of the Last K Numbers](https://leetcode.com/problems/product-of-the-last-k-numbers/)|[Python](/Medium/1352.ProductoftheLastKNumbers(BruteForce).py)|Medium|Brute Force|
|1352.|[Product of the Last K Numbers](https://leetcode.com/problems/product-of-the-last-k-numbers/)|[Python](/Medium/1352.ProductoftheLastKNumbers(MySolution).py)|Medium|Optimized, but overcode|
|1352.|[Product of the Last K Numbers](https://leetcode.com/problems/product-of-the-last-k-numbers/)|[Python](/Medium/1352.ProductoftheLastKNumbers(Revisited).py)|Medium||
|1357.|[Apply Discount Every n Orders](https://leetcode.com/problems/apply-discount-every-n-orders/)|[Python](/Medium/1357.ApplyDiscountEverynOrders(BruteForce).py)|Medium|Brute Force|
|1357.|[Apply Discount Every n Orders](https://leetcode.com/problems/apply-discount-every-n-orders/)|[Python](/Medium/1357.ApplyDiscountEverynOrders.py)|Medium|`Dictionary`|
|1361.|[Validate Binary Tree Nodes](https://leetcode.com/problems/validate-binary-tree-nodes/)|[Python](/Medium/1361.ValidateBinaryTreeNodes.py)|Medium|`BFS`, iteratively|
|1365.|[How Many Numbers Are Smaller Than the Current Number](https://leetcode.com/problems/how-many-numbers-are-smaller-than-the-current-number/)|[Python](/Easy/1365.HowManyNumbersAreSmallerThantheCurrentNumber.py)|Easy|`List comprehension`|
|1367.|[Linked List in Binary Tree](https://leetcode.com/problems/linked-list-in-binary-tree/)|[Python](/Medium/1367.LinkedListinBinaryTree.py)|Medium|`DFS`, `Linked List`, `Binary Tree`|
|1370.|[Increasing Decreasing String](https://leetcode.com/problems/increasing-decreasing-string/)|[Python](/Easy/1370.IncreasingDecreasingString.py)|Easy||
|1374.|[Generate a String With Characters That Have Odd Counts](https://leetcode.com/problems/generate-a-string-with-characters-that-have-odd-counts/)|[Python](/Easy/1374.GenerateaStringWithCharactersThatHaveOddCounts.py)|Easy||
|1379.|[Find a Corresponding Node of a Binary Tree in a Clone of That Tree](https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/)|[Python](/Medium/1379.FindaCorrespondingNodeofaBinaryTreeinaCloneofThatTree(iteratively).py)|Medium|`Stack`, iteratively|
|1379.|[Find a Corresponding Node of a Binary Tree in a Clone of That Tree](https://leetcode.com/problems/find-a-corresponding-node-of-a-binary-tree-in-a-clone-of-that-tree/)|[Python](/Medium/1379.FindaCorrespondingNodeofaBinaryTreeinaCloneofThatTree(recursion).py)|Medium|`DFS`, recursion|
|1380.|[Lucky Numbers in a Matrix](https://leetcode.com/problems/lucky-numbers-in-a-matrix/)|[Python](/Easy/1380.LuckyNumbersinaMatrix.py)|Easy|Nested `for` loops|
|1381.|[Design a Stack With Increment Operation](https://leetcode.com/problems/design-a-stack-with-increment-operation/)|[Python](/Medium/1381.DesignaStackWithIncrementOperation.py)|Medium|`List` as `Stack`|
|1387.|[Sort Integers by The Power Value](https://leetcode.com/problems/sort-integers-by-the-power-value/)|[Python](/Medium/1387.SortIntegersbyThePowerValue.py)|Medium||
|1389.|[Create Target Array in the Given Order](https://leetcode.com/problems/create-target-array-in-the-given-order/)|[Python](https://github.com/YuriSpiridonov/LeetCode/blob/master/Easy/1389.CreateTargetArrayintheGivenOrder.py)|Easy|`enumerate`, `insert`|
|1395.|[Count Number of Teams](https://leetcode.com/problems/count-number-of-teams/)|[Python](/Medium/1395.CountNumberofTeams.py)|Medium|Brute Force|
|1396.|[Design Underground System](https://leetcode.com/problems/design-underground-system/)|[Python](/Medium/1396.DesignUndergroundSystem.py)|Medium|`Dictionary`|
|1403.|[Minimum Subsequence in Non-Increasing Order](https://leetcode.com/problems/minimum-subsequence-in-non-increasing-order/)|[Python](/Easy/1403.MinimumSubsequenceinNon-IncreasingOrder(list).py)|Easy|`List`|
|1403.|[Minimum Subsequence in Non-Increasing Order](https://leetcode.com/problems/minimum-subsequence-in-non-increasing-order/)|[Python](/Easy/1403.MinimumSubsequenceinNon-IncreasingOrder.py)|Easy|sum (`int`) comparison|
|1409.|[Queries on a Permutation With Key](https://leetcode.com/problems/queries-on-a-permutation-with-key/)|[Python](/Medium/1409.QueriesonaPermutationWithKey.py)|Medium||
|1410.|[HTML Entity Parser](https://leetcode.com/problems/html-entity-parser/)|[Python](/Medium/1410.HTMLEntityParser.py)|Medium|`Re.sub`|
|1414.|[Find the Minimum Number of Fibonacci Numbers Whose Sum Is K](https://leetcode.com/problems/find-the-minimum-number-of-fibonacci-numbers-whose-sum-is-k/)|[Python](/Medium/1414.FindtheMinimumNumberofFibonacciNumbersWhoseSumIsK.py)|Medium|`Greedy`|
|1423.|[Maximum Points You Can Obtain from Cards](https://leetcode.com/problems/maximum-points-you-can-obtain-from-cards/)|[Python](/Medium/1423.MaximumPointsYouCanObtainfromCards.py)|Medium|`Sliding Window`|
|1426.|[Counting Elements](https://leetcode.com/problems/counting-elements)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%201/CountingElements.py)|Easy|
|1427.|[Perform String Shifts](https://leetcode.com/problems/perform-string-shifts)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%202/PerformStringShifts.py)|Easy|
|1428.|[Leftmost Column with at Least a One](https://leetcode.com/problems/leftmost-column-with-at-least-a-one)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%203/LeftmostColumnwithatLeastaOne.py)|Medium|
|1429.|[First Unique Number](https://leetcode.com/problems/first-unique-number/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%204/FirstUniqueNumber.py)|Medium|
|1430.|[Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree](https://leetcode.com/problems/check-if-a-string-is-a-valid-sequence-from-root-to-leaves-path-in-a-binary-tree/)|[Python](https://github.com/YuriSpiridonov/30-Day-LeetCoding-Challenge/blob/master/Week%205/CheckIfaStringIsaValidSequencefromRoottoLeavesPathinaBinaryTree.py)|Medium|
|1431.|[Kids With the Greatest Number of Candies](https://leetcode.com/problems/kids-with-the-greatest-number-of-candies/)|[Python](/Easy/1431.KidsWiththeGreatestNumberofCandies.py)|Easy|`List comprehension`|
|1436.|[Destination City](https://leetcode.com/problems/destination-city/)|[Python](/Easy/1436.DestinationCity(dict).py)|Easy|`Dictionary`|
|1436.|[Destination City](https://leetcode.com/problems/destination-city/)|[Python](/Easy/1436.DestinationCity(set).py)|Easy|`Set`|
|1437.|[Check If All 1's Are at Least Length K Places Away](https://leetcode.com/problems/check-if-all-1s-are-at-least-length-k-places-away/)|[Python](/Medium/1437.CheckIfAll1sAreatLeastLengthKPlacesAway.py)|Medium||
|1441.|[Build an Array With Stack Operations](https://leetcode.com/problems/build-an-array-with-stack-operations/)|[Python](/Easy/1441.BuildanArrayWithStackOperations.py)|Easy|`List`|
|1446.|[Consecutive Characters](https://leetcode.com/problems/consecutive-characters/)|[Python](/Easy/1446.ConsecutiveCharacters.py)|Easy|`Two pointers`|
|1448.|[Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree/)|[Python](/Medium/1448.CountGoodNodesinBinaryTree.py)|Medium|`DFS`, `Binary Tree`|
|1448.|[Count Good Nodes in Binary Tree](https://leetcode.com/problems/count-good-nodes-in-binary-tree/)|[Python](/Medium/1448.CountGoodNodesinBinaryTree(optimized).py)|Medium|optimized `DFS`, `Binary Tree`|
|1450.|[Number of Students Doing Homework at a Given Time](https://leetcode.com/problems/number-of-students-doing-homework-at-a-given-time/)|[Python](/Easy/1450.NumberofStudentsDoingHomeworkataGivenTime.py)|Easy|`Enumerate`|
|1455.|[Check If a Word Occurs As a Prefix of Any Word in a Sentence](https://leetcode.com/problems/check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence/)|[Python](/Easy/1455.CheckIfaWordOccursAsaPrefixofAnyWordinaSentence.py)|Easy|`Enumerate`|
|1457.|[Pseudo-Palindromic Paths in a Binary Tree](https://leetcode.com/problems/pseudo-palindromic-paths-in-a-binary-tree/)|[Python](/Medium/1457.Pseudo-PalindromicPathsinaBinaryTree.py)|Medium|`DFS`, `recursion`|
|1460.|[Make Two Arrays Equal by Reversing Sub-arrays](https://leetcode.com/problems/make-two-arrays-equal-by-reversing-sub-arrays/)|[Python](/Easy/1460.MakeTwoArraysEqualbyReversingSub-arrays.py)|Easy||
|1461.|[Check If a String Contains All Binary Codes of Size K](https://leetcode.com/problems/check-if-a-string-contains-all-binary-codes-of-size-k/)|[Python](/Medium/1461.CheckIfaStringContainsAllBinaryCodesofSizeK.py)|Medium|Brute Force|
|1463.|[Cherry Pickup II](https://leetcode.com/problems/cherry-pickup-ii/)|[Python](/Hard/1463.CherryPickupII.py)|Hard|`DFS`, `lfu cache`|
|1464.|[Maximum Product of Two Elements in an Array](https://leetcode.com/problems/maximum-product-of-two-elements-in-an-array/)|[Python](/Easy/1464.MaximumProductofTwoElementsinanArray.py)|Easy||
|1465.|[Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts](https://leetcode.com/problems/maximum-area-of-a-piece-of-cake-after-horizontal-and-vertical-cuts/)|[Python](/Medium/1465.MaximumAreaofaPieceofCakeAfterHorizontalandVerticalCuts.py)|Medium||
|1470.|[Shuffle the Array](https://leetcode.com/problems/shuffle-the-array/)|[Python](/Easy/1470.ShuffletheArray.py)|Easy|`Zip`|
|1472.|[Design Browser History](https://leetcode.com/problems/design-browser-history/)|[Python](/Medium/1472.DesignBrowserHistory.py)|Medium|`Doubly Linked List`|
|1472.|[Design Browser History](https://leetcode.com/problems/design-browser-history/)|[Python](/Medium/1472.DesignBrowserHistory(Dictionary).py)|Medium|`Dictionary`|
|1475.|[Final Prices With a Special Discount in a Shop](https://leetcode.com/problems/final-prices-with-a-special-discount-in-a-shop/)|[Python](/Easy/1475.FinalPricesWithaSpecialDiscountinaShop.py)|Easy|kinda Brute force|
|1476.|[Subrectangle Queries](https://leetcode.com/problems/subrectangle-queries/)|[Python](/Medium/1476.SubrectangleQueries.py)|Medium|nested `for loop`|
|1480.|[Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/)|[Python](/Easy/1480.RunningSumof1dArray.py)|Easy||
|1480.|[Running Sum of 1d Array](https://leetcode.com/problems/running-sum-of-1d-array/)|[Python](/Easy/1480.RunningSumof1dArray(ListComprehension).py)|Easy|`List comprehension`|
|1486.|[XOR Operation in an Array](https://leetcode.com/problems/xor-operation-in-an-array/)|[Python](/Easy/1486.XOROperationinanArray.py)|Easy||
|1487.|[Making File Names Unique](https://leetcode.com/problems/making-file-names-unique/)|[Python](/Medium/1487.MakingFileNamesUnique.py)|Medium||
|1491.|[Average Salary Excluding the Minimum and Maximum Salary](https://leetcode.com/problems/average-salary-excluding-the-minimum-and-maximum-salary/)|[Python](/Easy/1491.AverageSalaryExcludingtheMinimumandMaximumSalary.py)|Easy||
|1492.|[The kth Factor of n](https://leetcode.com/problems/the-kth-factor-of-n/)|[Python](/Medium/1492.ThekthFactorofn.py)|Medium||
|1496.|[Path Crossing](https://leetcode.com/problems/path-crossing/)|[Python](/Easy/1496.PathCrossing.py)|Easy||
|1502.|[Can Make Arithmetic Progression From Sequence](https://leetcode.com/problems/can-make-arithmetic-progression-from-sequence/)|[Python](/Easy/1502.CanMakeArithmeticProgressionFromSequence.py)|Easy||
|1507.|[Reformat Date](https://leetcode.com/problems/reformat-date/)|[Python](/Easy/1507.ReformatDate(List).py)|Easy|`List`|
|1507.|[Reformat Date](https://leetcode.com/problems/reformat-date/)|[Python](/Easy/1507.ReformatDate(String).py)|Easy|Without conberting `String` into `List`|
|1512.|[Number of Good Pairs](https://leetcode.com/problems/number-of-good-pairs/)|[Python](/Easy/1512.NumberofGoodPairs(Dict).py)|Easy|`Dictionary`|
|1512.|[Number of Good Pairs](https://leetcode.com/problems/number-of-good-pairs/)|[Python](/Easy/1512.NumberofGoodPairs(For).py)|Easy|Nested `for` loops|
|1518.|[Water Bottles](https://leetcode.com/problems/water-bottles/)|[Python](/Easy/1518.WaterBottles.py)|Easy|`While` loop|
|1523.|[Count Odd Numbers in an Interval Range](https://leetcode.com/problems/count-odd-numbers-in-an-interval-range/)|[Python](/Easy/1523.CountOddNumbersinanIntervalRange.py)|Easy||
|1528.|[Shuffle String](https://leetcode.com/problems/shuffle-string/)|[Python](/Easy/1528.ShuffleString(List).py)|Easy|`List`|
|1528.|[Shuffle String](https://leetcode.com/problems/shuffle-string/)|[Python](/Easy/1528.ShuffleString(String).py)|Easy|`String`|
|1534.|[Count Good Triplets](https://leetcode.com/problems/count-good-triplets/)|[Python](/Easy/1534.CountGoodTriplets.py)|Easy||
|1539.|[Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number/)|[Python](/Easy/1539.KthMissingPositiveNumber.py)|Easy|`List`|
|1544.|[Make The String Great](https://leetcode.com/problems/make-the-string-great/)|[Python](/Easy/1544.MakeTheStringGreat(Stack).py)|Easy|`Stack`|
|1544.|[Make The String Great](https://leetcode.com/problems/make-the-string-great/)|[Python](/Easy/1544.MakeTheStringGreat(string).py)|Easy|`String` in-place|
|1545.|[Find Kth Bit in Nth Binary String](https://leetcode.com/problems/find-kth-bit-in-nth-binary-string/)|[Python](/Medium/1545.FindKthBitinNthBinaryString.py)|Medium|Brute Force|
|1550.|[Three Consecutive Odds](https://leetcode.com/problems/three-consecutive-odds/)|[Python](/Easy/1550.ThreeConsecutiveOdds.py)|Easy|simple counter|
|1551.|[Minimum Operations to Make Array Equal](https://leetcode.com/problems/minimum-operations-to-make-array-equal/)|[Python](/Medium/1551.MinimumOperationstoMakeArrayEqual.py)|Medium||
|1556.|[Thousand Separator](https://leetcode.com/problems/thousand-separator/)|[Python](/Easy/1556.ThousandSeparator.py)|Easy|`String`, `List`|
|1557.|[Minimum Number of Vertices to Reach All Nodes](https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes/)|[Python](/Medium/1557.MinimumNumberofVerticestoReachAllNodes.py)|Medium|`Set`, kinda Brute Force|
|1561.|[Maximum Number of Coins You Can Get](https://leetcode.com/problems/maximum-number-of-coins-you-can-get/)|[Python](/Medium/1561.MaximumNumberofCoinsYouCanGet.py)|Medium||
|1566.|[Detect Pattern of Length M Repeated K or More Times](https://leetcode.com/problems/detect-pattern-of-length-m-repeated-k-or-more-times/)|[Python](/Easy/1566.DetectPatternofLengthMRepeatedKorMoreTimes.py)|Easy||
|1567.|[Maximum Length of Subarray With Positive Product](https://leetcode.com/problems/maximum-length-of-subarray-with-positive-product/)|[Python](/Medium/1567.MaximumLengthofSubarrayWithPositiveProduct.py)|Medium|kinda Brute force|
|1572.|[Matrix Diagonal Sum](https://leetcode.com/problems/matrix-diagonal-sum/)|[Python](/Easy/1572.MatrixDiagonalSum.py)|Easy||
|1576.|[Replace All ?'s to Avoid Consecutive Repeating Characters](https://leetcode.com/problems/replace-all-s-to-avoid-consecutive-repeating-characters/)|[Python](/Easy/1576.ReplaceAllQuestionmarkstoAvoidConsecutiveRepeatingCharacters.py)|Easy|Fast but awful soln.|
|1582.|[Special Positions in a Binary Matrix](https://leetcode.com/problems/special-positions-in-a-binary-matrix/)|[Python](/Easy/1582.SpecialPositionsinaBinaryMatrix.py)|Easy||
|1588.|[Sum of All Odd Length Subarrays](https://leetcode.com/problems/sum-of-all-odd-length-subarrays/)|[Python](/Easy/1588.SumofAllOddLengthSubarrays.py)|Easy|`Two Pointers`|
|1592.|[Rearrange Spaces Between Words](https://leetcode.com/problems/rearrange-spaces-between-words/)|[Python](/Easy/1592.RearrangeSpacesBetweenWords.py)|Easy||
|1598.|[Crawler Log Folder](https://leetcode.com/problems/crawler-log-folder/)|[Python](/Easy/1598.CrawlerLogFolder.py)|Easy||
|1603.|[Design Parking System](https://leetcode.com/problems/design-parking-system/)|[Python](/Easy/1603.DesignParkingSystem.py)|Easy|`Dictionary`|
|1609.|[Even Odd Tree](https://leetcode.com/problems/even-odd-tree/)|[Python](/Medium/1609.EvenOddTree.py)|Medium|`BFS`|
|1614.|[Maximum Nesting Depth of the Parentheses](https://leetcode.com/problems/maximum-nesting-depth-of-the-parentheses/)|[Python](/Easy/1614.MaximumNestingDepthoftheParentheses.py)|Easy||
|1619.|[Mean of Array After Removing Some Elements](https://leetcode.com/problems/mean-of-array-after-removing-some-elements/)|[Python](/Easy/1619.MeanofArrayAfterRemovingSomeElements.py)|Easy||
|1624.|[Largest Substring Between Two Equal Characters](https://leetcode.com/problems/largest-substring-between-two-equal-characters/)|[Python](/Easy/1624.LargestSubstringBetweenTwoEqualCharacters.py)|Easy||
|1629.|[Slowest Key](https://leetcode.com/problems/slowest-key/)|[Python](/Easy/1629.SlowestKey.py)|Easy||
|1630.|[Arithmetic Subarrays](https://leetcode.com/problems/arithmetic-subarrays/)|[Python](/Medium/1630.ArithmeticSubarrays.py)|Medium||
|1631.|[Path With Minimum Effort](https://leetcode.com/problems/path-with-minimum-effort/)|[Python](/Medium/1631.PathWithMinimumEffort.py)|Medium|`DFS`, `Binary Search`, Brute force|
|1636.|[Sort Array by Increasing Frequency](https://leetcode.com/problems/sort-array-by-increasing-frequency/)|[Python](/Easy/1636.SortArraybyIncreasingFrequency.py)|Easy|complicated counter|
|1637.|[Widest Vertical Area Between Two Points Containing No Points](https://leetcode.com/problems/widest-vertical-area-between-two-points-containing-no-points/)|[Python](/Medium/1637.WidestVerticalAreaBetweenTwoPointsContainingNoPoints.py)|Medium||
|1640.|[Check Array Formation Through Concatenation](https://leetcode.com/problems/check-array-formation-through-concatenation/)|[Python](/Easy/1640.CheckArraFormationThroughConcatenation.py)|Easy||
|1641.|[Count Sorted Vowel Strings](https://leetcode.com/problems/count-sorted-vowel-strings/)|[Python](/Medium/1641.CountSortedVowelStrings.py)|Medium|`itertools`|
|1646.|[Get Maximum in Generated Array](https://leetcode.com/problems/get-maximum-in-generated-array/)|[Python](/Easy/1646.GetMaximuminGeneratedArray(while).py)|Easy|`while`|
|1646.|[Get Maximum in Generated Array](https://leetcode.com/problems/get-maximum-in-generated-array/)|[Python](/Easy/1646.GetMaximuminGeneratedArray.py)|Easy|`for`|
|1652.|[Defuse the Bomb](https://leetcode.com/problems/defuse-the-bomb/)|[Python](/Easy/1652.DefusetheBomb.py)|Easy||
|1656.|[Design an Ordered Stream](https://leetcode.com/problems/design-an-ordered-stream/)|[Python](/Easy/1656.DesignanOrderedStream.py)|Easy|`list`|
|1657.|[Determine if Two Strings Are Close](https://leetcode.com/problems/determine-if-two-strings-are-close/)|[Python](/Medium/1657.DetermineifTwoStringsAreClose.py)|Medium|`collections.Counter`|
|1658.|[Minimum Operations to Reduce X to Zero](https://leetcode.com/problems/minimum-operations-to-reduce-x-to-zero/)|[Python](/Medium/1658.MinimumOperationstoReduceXtoZero.py)|Medium||
|1662.|[Check If Two String Arrays are Equivalent](https://leetcode.com/problems/check-if-two-string-arrays-are-equivalent/)|[Python](/Easy/1662.CheckIfTwoStringArraysareEquivalent.py)|Easy|`.join()`|
|1663.|[Smallest String With A Given Numeric Value](https://leetcode.com/problems/smallest-string-with-a-given-numeric-value/)|[Python](/Medium/1663.SmallestStringWithAGivenNumericValue.py)|Medium||
|1668.|[Maximum Repeating Substring](https://leetcode.com/problems/maximum-repeating-substring/)|[Python](/Easy/1668.MaximumRepeatingSubstring.py)|Easy||
|1669.|[Merge In Between Linked Lists](https://leetcode.com/problems/merge-in-between-linked-lists/)|[Python](/Medium/1669.MergeInBetweenLinkedLists.py)|Medium|`Linked List`|
|1670.|[Design Front Middle Back Queue](https://leetcode.com/problems/design-front-middle-back-queue/)|[Python](/Medium/1670.DesignFrontMiddleBackQueue.py)|Medium|`List`|
|1672.|[Richest Customer Wealth](https://leetcode.com/problems/richest-customer-wealth/)|[Python](/Easy/1672.RichestCustomerWealth.py)|Easy||
|1673.|[Find the Most Competitive Subsequence](https://leetcode.com/problems/find-the-most-competitive-subsequence/)|[Python](/Medium/1673.FindtheMostCompetitiveSubsequence.py)|Medium|`Stack`|
|1678.|[Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation/)|[Python](/Easy/1678.GoalParserInterpretation(replace).py)|Easy|`.replace()`|
|1678.|[Goal Parser Interpretation](https://leetcode.com/problems/goal-parser-interpretation/)|[Python](/Easy/1678.GoalParserInterpretation.py)|Easy|iteratively|
|1679.|[Max Number of K-Sum Pairs](https://leetcode.com/problems/max-number-of-k-sum-pairs/)|[Python](/Medium/1679.MaxNumberofK-SumPairs.py)|Medium|`collections`, `Counter`|
|1680.|[Concatenation of Consecutive Binary Numbers](https://leetcode.com/problems/concatenation-of-consecutive-binary-numbers/)|[Python](/Medium/1680.ConcatenationofConsecutiveBinaryNumbers.py)|Medium||
|1684.|[Count the Number of Consistent Strings](https://leetcode.com/problems/count-the-number-of-consistent-strings/)|[Python](/Easy/1684.CounttheNumberofConsistentStrings.py)|Easy||
|1685.|[Sum of Absolute Differences in a Sorted Array](https://leetcode.com/problems/sum-of-absolute-differences-in-a-sorted-array/)|[Python](/Medium/1685.SumofAbsoluteDifferencesinaSortedArray.py)|Medium||
|1688.|[Count of Matches in Tournament](https://leetcode.com/problems/count-of-matches-in-tournament/)|[Python](/Easy/1688.CountofMatchesinTournament.py)|Easy|simple counter|
|1689.|[Partitioning Into Minimum Number Of Deci-Binary Numbers](https://leetcode.com/problems/partitioning-into-minimum-number-of-deci-binary-numbers/)|[Python](/Medium/1689.PartitioningIntoMinimumNumberOfDeci-BinaryNumbers.py)|Medium|`max()`|
|1694.|[Reformat Phone Number](https://leetcode.com/problems/reformat-phone-number/)|[Python](/Easy/1694.ReformatPhoneNumber.py)|Easy||
|1695.|[Maximum Erasure Value](https://leetcode.com/problems/maximum-erasure-value/)|[Python](/Medium/1695.MaximumErasureValue.py)|Medium||
|1700.|[Number of Students Unable to Eat Lunch](https://leetcode.com/problems/number-of-students-unable-to-eat-lunch/)|[Python](/Easy/1700.NumberofStudentsUnabletoEatLunch.py)|Easy|simple counter|
|1704.|[Determine if String Halves Are Alike](https://leetcode.com/problems/determine-if-string-halves-are-alike/)|[Python](/Easy/1704.DetermineifStringHalvesAreAlike.py)|Easy|simple counter|
|1710.|[Maximum Units on a Truck](https://leetcode.com/problems/maximum-units-on-a-truck/)|[Python](/Easy/1710.MaximumUnitsonaTruck.py)|Easy|`Dictionary`|
|1716.|[Calculate Money in Leetcode Bank](https://leetcode.com/problems/calculate-money-in-leetcode-bank/)|[Python](/Easy/1716.CalculateMoneyinLeetcodeBank.py)|Easy||
|1720.|[Decode XORed Array](https://leetcode.com/problems/decode-xored-array/)|[Python](/Easy/1720.DecodeXORedArray.py)|Easy||
|1721.|[Swapping Nodes in a Linked List](https://leetcode.com/problems/swapping-nodes-in-a-linked-list/)|[Python](/Medium/1721.SwappingNodesinaLinkedList.py)|Medium|`Linked List`, `Queue`|
|1725.|[Number Of Rectangles That Can Form The Largest Square](https://leetcode.com/problems/number-of-rectangles-that-can-form-the-largest-square/)|[Python](/Easy/1725.NumberOfRectanglesThatCanFormTheLargestSquare.py)|Easy|`collections.defaultdict`|
|1732.|[Find the Highest Altitude](https://leetcode.com/problems/find-the-highest-altitude/)|[Python](/Easy/1732.FindtheHighestAltitude.py)|Easy||
|1748.|[Sum of Unique Elements](https://leetcode.com/problems/sum-of-unique-elements/)|[Python](/Easy/1748.SumofUniqueElements.py)|Easy|`collections.Counter`|
|1752.|[Check if Array Is Sorted and Rotated](https://leetcode.com/problems/check-if-array-is-sorted-and-rotated/)|[Python](/Easy/1752.CheckifArrayIsSortedandRotated.py)|Easy||
|1773.|[Count Items Matching a Rule](https://leetcode.com/problems/count-items-matching-a-rule/)|[Python](/Easy/1773.CountItemsMatchingaRule.py)|Easy||
|1790.|[Check if One String Swap Can Make Strings Equal](https://leetcode.com/problems/check-if-one-string-swap-can-make-strings-equal/)|[Python](/Easy/1790.CheckifOneStringSwapCanMakeStringsEqual.py)|Easy||
|1791.|[Find Center of Star Graph](https://leetcode.com/problems/find-center-of-star-graph/)|[Python](/Medium/1791.FindCenterofStarGraph.py)|Medium||
|1796.|[Second Largest Digit in a String](https://leetcode.com/problems/second-largest-digit-in-a-string/)|[Python](/Easy/1796.SecondLargestDigitinaString.py)|Easy||
|1800.|[Maximum Ascending Subarray Sum](https://leetcode.com/problems/maximum-ascending-subarray-sum/)|[Python](/Easy/1800.MaximumAscendingSubarraySum.py)|Easy||
|1805.|[Number of Different Integers in a String](https://leetcode.com/problems/number-of-different-integers-in-a-string/)|[Python](/Easy/1805.NumberofDifferentIntegersinaString.py)|Easy||
|1812.|[Determine Color of a Chessboard Square](https://leetcode.com/problems/determine-color-of-a-chessboard-square/)|[Python](/Easy/1812.DetermineColorofaChessboardSquare.py)|Easy||
|1816.|[Truncate Sentence](https://leetcode.com/problems/truncate-sentence/)|[Python](/Easy/1816.TruncateSentence.py)|Easy||

## License
The code is open-source and licensed under the [MIT license](/LICENSE).

LeetCode

LeetCode Latest Version Download

Today's picks

Was this content helpful?

Recent Feedback

LeetCode

LeetCode Latest Version Download

Today's picks

Was this content helpful?

Recent Feedback

Download README