100-DSA-Interview-Problems

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100-DSA-Interview-Problems

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100 DSA Problems and solutions from leetcode

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# DSA 100 Challenge

100 DSA interview problems with solutions

![](https://mrsohan.netlify.app/static/media/work9.2ca549284563f79a8204.png)

## Introduction

This repository is your go-to resource for mastering Data Structures and Algorithms. I have curated a list of the top 100 DSA problems from LeetCode, covering a wide array of topics such as Array, String, Linked List, Graph, Dynamic Programming, Tree, Stack and Queue, and Miscellaneous. These problems are carefully selected to provide a comprehensive understanding of essential DSA concepts.

## Problem Categories

- Array
- String
- Linked List
- Graph
- Dynamic Programming
- Tree
- Stack and Queue
- Misc

| Array | Problem                                          | LeetCode Link                                                                           | Difficulty Level | Solution |
| ----- | ------------------------------------------------ | --------------------------------------------------------------------------------------- | ---------------- | -------- |
| 1     | Check if pair with the given Sum exists in Array | [Link](https://leetcode.com/problems/two-sum/description/)                              | Easy             |          |
| 2     | Best Time to Buy and Sell Stock                  | [Link](https://leetcode.com/problems/best-time-to-buy-and-sell-stock/description/)      | Easy             |          |
| 3     | Find duplicates                                  | [Link](https://leetcode.com/problems/find-the-duplicate-number/description/)            | Medium           |          |
| 4     | Product of Array Except Self                     | [Link](https://leetcode.com/problems/product-of-array-except-self/description/)         | Medium           |          |
| 5     | Maximum Subarray                                 | [Link](https://leetcode.com/problems/maximum-subarray/description/)                     | Easy             |          |
| 6     | Maximum Product Subarray                         | [Link](https://leetcode.com/problems/maximum-product-subarray/description/)             | Medium           |          |
| 7     | Find Minimum in Rotated Sorted Array             | [Link](https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/) | Medium           |          |
| 8     | Search in Rotated Sorted Array                   | [Link](https://leetcode.com/problems/search-in-rotated-sorted-array/description/)       | Medium           |          |
| 9     | 3 Sum                                            | [Link](https://leetcode.com/problems/3sum/description/)                                 | Medium           |          |
| 10    | Container With Most Water                        | [Link](https://leetcode.com/problems/container-with-most-water/description/)            | Medium           |          |
| 11    | Find the Factorial of a large number             | [Link](https://leetcode.com/problems/factorial-trailing-zeroes/description/)            | Medium           |          |
| 12    | Trapping Rain Water                              | [Link](https://leetcode.com/problems/trapping-rain-water/description/)                  | Hard             |          |
| 13    | Chocolate Distribution Problem                   | [Link](https://leetcode.com/problems/collecting-chocolates/description/)                | Medium           |          |
| 14    | Insert Interval                                  | [Link](https://leetcode.com/problems/insert-interval/description/)                      | Hard             |          |
| 15    | Merge Intervals                                  | [Link](https://leetcode.com/problems/merge-intervals/description/)                      | Medium           |          |
| 16    | Non-overlapping Intervals                        | [Link](https://leetcode.com/problems/non-overlapping-intervals/description/)            | Medium           |          |
| 17    | Set Matrix Zeroes                                | [Link](https://leetcode.com/problems/set-matrix-zeroes/description/)                    | Medium           |          |
| 18    | Spiral Matrix                                    | [Link](https://leetcode.com/problems/spiral-matrix/description/)                        | Medium           |          |

| String | Problem                                                               | LeetCode Link                                                                                     | Difficulty Level | Solution |
| ------ | --------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------- | ---------------- | -------- |
| 1      | Longest Substring Without Repeating Characters                        | [Link](https://leetcode.com/problems/longest-substring-without-repeating-characters/description/) | Medium           |          |
| 2      | Longest Repeating Character Replacement                               | [Link](https://leetcode.com/problems/longest-repeating-character-replacement/description/)        | Medium           |          |
| 3      | Smallest window in a String containing all characters of other String | [Link](https://leetcode.com/problems/minimum-window-substring/description/)                       | Hard             |          |
| 4      | Check whether two Strings are anagram of each other                   | [Link](https://leetcode.com/problems/valid-anagram/description/)                                  | Easy             |          |
| 5      | Print all anagrams together                                           | [Link](https://leetcode.com/problems/group-anagrams/description/)                                 | Medium           |          |

| Linked List | Problem                                            | LeetCode Link                                                                       | Difficulty Level | Solution  |
| ----------- | -------------------------------------------------- | ----------------------------------------------------------------------------------- | ---------------- | --------- |
| 1           | Reverse a Linked List                              | [Link](https://leetcode.com/problems/reverse-linked-list/description/)              | Easy             | [Link](#) |
| 2           | Detect Cycle in a Linked List                      | [Link](https://leetcode.com/problems/linked-list-cycle/description/)                | Medium           | [Link](#) |
| 3           | Merge Two Sorted Lists                             | [Link](https://leetcode.com/problems/merge-two-sorted-lists/description/)           | Easy             | [Link](#) |
| 4           | Merge K Sorted Lists                               | [Link](https://leetcode.com/problems/merge-k-sorted-lists/description/)             | Hard             | [Link](#) |
| 5           | Remove Nth Node From End Of List                   | [Link](https://leetcode.com/problems/remove-nth-node-from-end-of-list/description/) | Medium           | [Link](#) |
| 6           | Reorder List                                       | [Link](https://leetcode.com/problems/reorder-list/description/)                     | Medium           | [Link](#) |
| 7           | Add 1 to a number represented as linked list       | [Link](#)                                                                           | Medium           | [Link](#) |
| 8           | Find the middle of a given linked list             | [Link](https://leetcode.com/problems/middle-of-the-linked-list/description/)        | Easy             | [Link](#) |
| 9           | Delete last occurrence of an item from linked list | [Link](https://leetcode.com/problems/remove-linked-list-elements/description/)      | Easy             | [Link](#) |

| Stack and Queue | Problem                                                  | LeetCode Link                                                        | Difficulty Level | Solution  |
| --------------- | -------------------------------------------------------- | -------------------------------------------------------------------- | ---------------- | --------- |
| 1               | Check if given Parentheses expression is balanced or not | [Link](https://leetcode.com/problems/valid-parentheses/description/) | Easy             | [Link](#) |
| 2               | Delete middle element of a stack                         | [Link](#)                                                            | Medium           | [Link](#) |

| Tree and Graph | Problem                                                   | LeetCode Link | Difficulty Level | Solution |
| -------------- | --------------------------------------------------------- | ------------- | ---------------- | -------- |
| 1              | Invert/Flip Binary Tree                                   | [Link](#)     | Easy             |          |
| 2              | Binary Tree Maximum Path Sum                              | [Link](#)     | Hard             |          |
| 3              | Binary Tree Level Order Traversal                         | [Link](#)     | Medium           |          |
| 4              | Serialize and Deserialize Binary Tree                     | [Link](#)     | Hard             |          |
| 5              | Subtree of Another Tree                                   | [Link](#)     | Easy             |          |
| 6              | Construct Binary Tree from Preorder and Inorder Traversal | [Link](#)     | Medium           |          |
| 7              | Validate Binary Search Tree                               | [Link](#)     | Medium           |          |
| 8              | Kth Smallest Element in a BST                             | [Link](#)     | Medium           |          |
| 9              | Lowest Common Ancestor of BST                             | [Link](#)     | Easy             |          |
| 10             | Implement Trie (Prefix Tree)                              | [Link](#)     | Medium           |          |
| 11             | Add and Search Word                                       | [Link](#)     | Medium           |          |

| Dynamic Programming | Problem                                            | LeetCode Link | Difficulty Level | Solution |
| ------------------- | -------------------------------------------------- | ------------- | ---------------- | -------- |
| 1                   | Coin Change                                        | [Link](#)     | Medium           |          |
| 2                   | 0/1 Knapsack Problem                               | [Link](#)     | Medium           |          |
| 3                   | Longest Increasing Subsequence                     | [Link](#)     | Medium           |          |
| 4                   | Longest Common Subsequence                         | [Link](#)     | Medium           |          |
| 5                   | Word Break Problem                                 | [Link](#)     | Medium           |          |
| 6                   | Dice Throw                                         | [Link](#)     | Medium           |          |
| 7                   | Egg Dropping Puzzle                                | [Link](#)     | Hard             |          |
| 8                   | Matrix Chain Multiplication                        | [Link](#)     | Medium           |          |
| 9                   | Combination Sum                                    | [Link](#)     | Medium           |          |
| 10                  | Subset Sum Problem                                 | [Link](#)     | Medium           |          |
| 11                  | Find maximum possible stolen value from houses     | [Link](#)     | Medium           |          |
| 12                  | Count Possible Decodings of a given Digit Sequence | [Link](#)     | Medium           |          |
| 13                  | Unique paths in a Grid with Obstacles              | [Link](#)     | Medium           |          |
| 14                  | Jump Game                                          | [Link](#)     | Medium           |          |
| 15                  | Cutting a Rod                                      | [Link](#)     | Medium           |          |
| 16                  | Maximum Product Cutting                            | [Link](#)     | Medium           |          |
| 17                  | Count number of ways to cover a distance           | [Link](#)     | Easy             |          |
| 18                  | Number of 1 Bits                                   | [Link](#)     | Easy             |          |
| 19                  | Counting Bits                                      | [Link](#)     | Medium           |          |
| 20                  | Missing Number                                     | [Link](#)     | Easy             |          |
| 21                  | Reverse Bits                                       | [Link](#)     | Easy             |          |
| 22                  | Find XOR of all subsets of a set                   | [Link](#)     | Medium           |          |

| Graph | Problem                                         | LeetCode Link | Difficulty Level | Solution |
| ----- | ----------------------------------------------- | ------------- | ---------------- | -------- |
| 1     | Detect Cycle in a Directed Graph                | [Link](#)     | Medium           |          |
| 2     | Bridges in a graph                              | [Link](#)     | Hard             |          |
| 3     | Check whether a given graph is Bipartite or not | [Link](#)     | Medium           |          |
| 4     | Strongly Connected Components                   | [Link](#)     | Hard             |          |
| 5     | Topological Sorting                             | [Link](#)     | Medium           |          |

| Miscellaneous | Problem                                                   | LeetCode Link | Difficulty Level | Solution |
| ------------- | --------------------------------------------------------- | ------------- | ---------------- | -------- |
| 1             | Sentence Palindrome                                       | [Link](#)     | Easy             |          |
| 2             | Palindromic Substrings                                    | [Link](#)     | Medium           |          |
| 3             | Longest Common Prefix                                     | [Link](#)     | Easy             |          |
| 4             | Print Right View of a Binary Tree                         | [Link](#)     | Medium           |          |
| 5             | Find the first circular tour that visits all petrol pumps | [Link](#)     | Medium           |          |
| 6             | Length of the longest valid substring                     | [Link](#)     | Hard             |          |
| 7             | Find the XOR of all subsets of a set                      | [Link](#)     | Medium           |          |
| 8             | Detect Cycle in a Directed Graph                          | [Link](#)     | Medium           |          |
| 9             | Bridges in a graph                                        | [Link](#)     | Medium           |          |
| 10            | Check whether a given graph is Bipartite or not           | [Link](#)     | Medium           |          |
| 12            | Find size of the largest region in Boolean Matrix         | [Link](#)     | Medium           |          |
| 13            | Flood fill Algorithm                                      | [Link](#)     | Medium           |          |
| 14            | Strongly Connected Components                             | [Link](#)     | Medium           |          |
| 15            | Topological Sorting                                       | [Link](#)     | Medium           |          |
| 16            | Count ways to reach the n’th stair                        | [Link](#)     | Easy             |          |
| 17            | Coin Change                                               | [Link](#)     | Medium           |          |
| 18            | 0/1 Knapsack Problem                                      | [Link](#)     | Medium           |          |
| 19            | Longest Increasing Subsequence                            | [Link](#)     | Medium           |          |

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