450-dsa

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Repository with 450+ DSA problems covering all major patterns like arrays, DP, graphs, trees, and more. Includes clean, optimized solutions focused on pattern-based learning for coding interviews and problem-solving.

450-dsa 최신버젼 다운로드

최종 버전 다운로드 (.zip)

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# 450 DSA Tracker

🌐 **Live Demo:** [https://450-ds.vercel.app](https://450-ds.vercel.app)

Track your progress through Love Babbar's 450 DSA problems — with platform sync, leaderboard, and more.

[![Open For PR](https://img.shields.io/badge/Open%20For-PR-orange?style=for-the-badge&logo=github)](https://github.com/mohitkumhar/450-dsa)
[![Security Policy](https://img.shields.io/badge/Security-Policy-red?style=flat&logo=shield)](https://raw.githubusercontent.com/mohitkumhar/450-dsa/main/SECURITY.md)
[![Code Style](https://img.shields.io/badge/Code%20Style-PEP8-blue?style=flat&logo=python)](https://peps.python.org/pep-0008/)
![Python](https://img.shields.io/badge/Python-3.10+-blue?style=flat&logo=python)
![Flask](https://img.shields.io/badge/Flask-2.3-black?style=flat&logo=flask)
![MongoDB](https://img.shields.io/badge/MongoDB-Atlas-green?style=flat&logo=mongodb)

---

## What is this?

A full-stack Flask web app to help you track, manage, and share your DSA journey. Originally a React + LocalBase project, it's been completely rewritten in Python with MongoDB as the database.

---

## Features

- **Topic-wise tracking** — browse all 24 DSA topics and mark questions done
- **Bookmarks** — save questions for quick review
- **Notes** — write and save personal notes per question
- **Search** — full-text search with topic, difficulty, platform, and status filters
- **OAuth login** — sign in with GitHub or Google, or register with email/password
- **Platform sync** — connect LeetCode, GFG, GitHub, HackerRank, Coding Ninjas, AtCoder, and Codewars and pull your stats
- **Profile dashboard** — activity heatmap, rating chart, difficulty breakdown, badges
- **Leaderboard** — ranked by C-Score (composite score across all platforms)
- **Public profiles** — shareable profile cards
- **Admin panel** — manage users and content
- **Export notes** — download your notes as Markdown
- **Docker support** — run the whole app with one command

---

## Platform Sync Guide

### Supported Platforms

The platform sync feature currently supports:

- LeetCode
- GitHub
- GeeksforGeeks (GFG)
- HackerRank
- Coding Ninjas
- AtCoder
- Codewars

### Username and Profile Formats

Provide the platform username or handle for supported platforms.

For Coding Ninjas, you may provide either:

- A profile ID
- A full Coding Ninjas profile URL

### Sync Cooldown

Platform sync requests are rate limited to avoid excessive requests to external services.

After a sync attempt, users must wait **10 minutes** before starting another sync. If a sync is attempted before the cooldown expires, the remaining wait time is returned in the response.

### Sync Status Indicators

Each platform reports its sync result independently:

| Status    | Meaning                                       |
| --------- | --------------------------------------------- |
| `synced`  | Platform data was fetched successfully        |
| `failed`  | Platform data could not be fetched            |
| `skipped` | Platform was not included in the sync request |

### Partial Success Handling

Platform sync operations are processed independently.

- If at least one platform syncs successfully, the overall request is considered successful.
- If some platforms succeed and others fail, the response includes `partial_success: true`.
- If all requested platforms fail, the sync request is considered unsuccessful.
- If no platforms are provided, no sync attempt is performed.

### Troubleshooting

Common causes of sync failures include:

- Invalid username or handle
- Incorrect Coding Ninjas profile ID or URL
- No solved problems found on the platform
- External API rate limits
- Temporary platform outages
- External service errors

If a platform fails to sync, verify the supplied username or profile information and try again later.

> **Note:** If you recently changed your username on a platform,
> allow some time for the change to propagate before syncing again.

## Quick Start

### Option 1 — Local setup

**1. Clone and set up environment**

```bash
git clone https://github.com/mohitkumhar/450-dsa.git
cd 450-dsa
python -m venv venv

# Windows
venv\Scripts\activate

# macOS/Linux
source venv/bin/activate

pip install -r requirements.txt

# For development, linting, and tests
pip install -r requirements-dev.txt
```

**2. Configure environment variables**

```bash
cp .env.example .env   # macOS/Linux
copy .env.example .env  # Windows
```

Edit `.env` and fill in your values:

```env
# REQUIRED - generate your own first:
# python -c "import secrets; print(secrets.token_hex(32))"
SECRET_KEY=replace-this-with-a-real-secret

# MongoDB — use Atlas (free) or local
MONGO_URI=mongodb+srv://<user>:<password>@cluster.mongodb.net/dsa_tracker

# GitHub OAuth (optional)
GITHUB_CLIENT_ID=your-github-client-id
GITHUB_CLIENT_SECRET=your-github-client-secret

# Google OAuth (optional)
GOOGLE_CLIENT_ID=your-google-client-id
GOOGLE_CLIENT_SECRET=your-google-client-secret

# Cloudinary — for profile photo uploads (optional)
CLOUDINARY_CLOUD_NAME=your-cloud-name
CLOUDINARY_API_KEY=your-api-key
CLOUDINARY_API_SECRET=your-api-secret
```

The app warns and generates a temporary `SECRET_KEY` if the variable is missing or still set to an insecure placeholder. Set a real generated secret in deployed environments so user sessions persist across restarts. If a secret was ever committed or shared, rotate it before running the app again.

**3. Run**

```bash
python run.py
```

Open `http://localhost:5000` in your browser. The app seeds all 450+ questions from `data.json` on first run.

---

### Option 2 — Docker

```bash
git clone https://github.com/mohitkumhar/450-dsa.git
cd 450-dsa
docker compose up
```

Open `http://localhost:5000`.

---

## Project Structure

```
450-dsa/
├── app/
│   ├── __init__.py          # App factory
│   ├── extensions.py        # Shared Flask extensions (db, bcrypt, limiter...)
│   ├── utils.py             # Helpers, search logic, leaderboard scoring
│   ├── auth/                # Login, register, OAuth (GitHub, Google)
│   ├── tracker/             # Topics, questions, bookmarks, notes
│   ├── profile/             # Profile page, platform sync, photo upload
│   ├── search/              # Search API with filters
│   ├── leaderboard/         # Leaderboard routes and API
│   ├── admin/               # Admin dashboard
│   ├── public/              # Public profile pages
│   ├── faq/                 # FAQ page
│   └── platforms/
│       └── fetchers.py      # LeetCode, GFG, GitHub, HackerRank, Coding Ninjas fetchers
├── templates/               # Jinja2 HTML templates
├── static/                  # CSS and JS assets
├── tests/                   # Pytest test suite
├── data.json                # All 450+ DSA questions
├── run.py                   # App entry point
├── requirements.txt         # Python dependencies
├── requirements-dev.txt     # Dev/test dependencies
├── .env.example             # Environment variable template
├── Dockerfile
└── docker-compose.yml
```

---

## Database

The app uses **MongoDB** (via Flask-PyMongo). There is no SQLite or SQLAlchemy — those were part of an earlier version.

**Collections:**

- `user` — user accounts, progress, platform usernames, external stats
- `topic` — DSA topic names and ordering
- `question` — all 450+ problems with URLs

MongoDB is accessed through `app.extensions.db` (a `LocalProxy` to `mongo.db`). All indexes are created on startup in `app/__init__.py`.

You can use [MongoDB Atlas](https://cloud.mongodb.com) (free M0 tier) or a local MongoDB instance.

---

## API Endpoints

| Method | Endpoint                | Description                                                                        |
| ------ | ----------------------- | ---------------------------------------------------------------------------------- |
| GET    | `/`                     | Dashboard — all topics with progress                                               |
| GET    | `/topic/<id>`           | Questions for a topic                                                              |
| GET    | `/search`               | Search page                                                                        |
| GET    | `/bookmarks`            | Saved bookmarks                                                                    |
| GET    | `/profile`              | User profile dashboard                                                             |
| GET    | `/leaderboard`          | Global leaderboard                                                                 |
| GET    | `/u/<user_id>`          | Public profile                                                                     |
| GET    | `/api/search_questions` | Search API (supports `q`, `topic_id`, `difficulty`, `platform`, `status`, `limit`) |
| GET    | `/api/leaderboard`      | Leaderboard API (supports `mode`: cscore, questions, rating, college)              |
| POST   | `/update_question/<id>` | Update done/bookmark/notes for a question                                          |
| POST   | `/sync_platforms`       | Sync external platform stats                                                       |
| POST   | `/edit_profile`         | Update profile fields                                                              |
| POST   | `/upload_photo`         | Upload profile photo                                                               |
| POST   | `/delete_account`       | Permanently delete account (GDPR)                                                  |
| GET    | `/search_universities`  | University autocomplete                                                            |

---

## Tech Stack

| Layer         | Technology                                 |
| ------------- | ------------------------------------------ |
| Backend       | Flask 2.3                                  |
| Database      | MongoDB (Flask-PyMongo)                    |
| Auth          | Flask-Login, Flask-Bcrypt, Authlib (OAuth) |
| Rate limiting | Flask-Limiter                              |
| Frontend      | Jinja2, Bootstrap Icons, Chart.js          |
| Photo storage | Cloudinary                                 |
| Testing       | Pytest                                     |
| Deployment    | Docker, Vercel                             |

---

## Running Tests

```bash
pip install -r requirements-dev.txt
pytest
```

---

## Environment Variables Reference

| Variable                | Required    | Description                                                                                                                                                      |
| ----------------------- | ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `SECRET_KEY`            | Recommended | Flask session secret. Must be a real generated secret, not a placeholder. Missing or insecure values fall back to a temporary key and reset sessions on restart. |
| `MONGO_URI`             | Yes         | MongoDB connection string                                                                                                                                        |
| `GITHUB_CLIENT_ID`      | No          | GitHub OAuth app client ID                                                                                                                                       |
| `GITHUB_CLIENT_SECRET`  | No          | GitHub OAuth app client secret                                                                                                                                   |
| `GOOGLE_CLIENT_ID`      | No          | Google OAuth client ID                                                                                                                                           |
| `GOOGLE_CLIENT_SECRET`  | No          | Google OAuth client secret                                                                                                                                       |
| `CLOUDINARY_CLOUD_NAME` | No          | Cloudinary cloud name for photo uploads                                                                                                                          |
| `CLOUDINARY_API_KEY`    | No          | Cloudinary API key                                                                                                                                               |
| `CLOUDINARY_API_SECRET` | No          | Cloudinary API secret                                                                                                                                            |

---

## Credits

- DSA problem set curated by **[Love Babbar](https://www.youtube.com/@LoveBabbar)** — [450 DSA Cracker Sheet](https://450dsa.com)
- Flask conversion and ongoing development by the open-source community

---

## Contributing

PRs are welcome! Please read [CONTRIBUTING.md](CONTRIBUTING.md) before opening one.

### GSSoC Flask Redis Caching Guide

- Enable Redis cache invalidation on list updates.

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