LeetCode Predictions Viewer 📈

A full-stack web application that predicts LeetCode contest rating changes and compares them with actual contest results after the contest ends.

Built using FastAPI for the backend and React + Vite for the frontend, with Firebase integration for user grouping.

---

✨ What This Project Does

• Fetches the predictions of rating changes for LeetCode Weekly & Biweekly contests from lccn.lbao.site

• Fetches actual contest performance using LeetCode GraphQL

• Supports multiple users via:

  • Channel ID (Firebase)
  • Manual username input

• Displays results in a retro terminal-style UI

• Uses LRU caching for fast repeated queries

• Supports fallback backend URLs for reliability

---

🧱 Architecture Overview

Frontend (React + Vite)
        |
        |  REST API
        ↓
Backend (FastAPI)
        |
        ├── LeetCode GraphQL
        ├── Firebase (channels → users)
        └── LRU Cache

---

📂 Repository Structure

.
├── fast-api-backend/      # FastAPI backend
│   ├── main.py
│   ├── routers/
│   ├── helpers/
│   ├── middleware/
│   ├── models/
│   └── README.md          # Backend documentation (detailed)
│
└── frontend-vite/         # React + Vite frontend
    ├── src/
    ├── index.html
    ├── vite.config.js
    └── README.md

---

🚀 Quick Start (Local Development)

1️⃣ Backend Setup

cd fast-api-backend
uv sync
python start.py

Backend runs at:

http://localhost:7667

Docs:

• Swagger → http://localhost:7667/docs
• ReDoc → http://localhost:7667/redoc

📘 Detailed backend setup: ➡️ fast-api-backend/README.md

---

2️⃣ Frontend Setup

cd frontend-vite
npm install
npm run dev

Frontend runs at:

http://localhost:5173

---

🔌 Environment Configuration

Backend (fast-api-backend/.env)

PORT=7667
FIREBASE_CREDENTIALS_PATH=db_config/your-firebase.json
ALLOWED_ORIGINS=http://localhost:5173

Frontend (frontend-vite/.env.development)

VITE_API_BASE_URL=http://localhost:7667
VITE_API_BASE_URL_1=https://localhost:7768

---

📡 API Endpoints

Endpoint	Method	Purpose
/health	GET	Health check
/lc	GET	Rating predictions from lccn.lbao.site
/obtained	GET	Actual contest results from LeetCode GraphQL
/cache/clear	POST	Clear backend cache

(See backend README for full request/response formats)

---

🎨 Frontend Highlights

• Retro CRT terminal UI

• Light / Dark theme toggle

• Parallel fetching of:

  • Predictions
  • Actual ratings

• Graceful fallback to secondary backend

• Responsive layout (mobile friendly)

---

🔮 Future Improvements

• Redis instead of in-memory cache
• Discord bot integration
• Admin dashboard

---

👨‍💻 Author

Sai Deekshith Konda and Yashwanth Reddy LeetCode • Backend • Full-Stack Development