LCid - access LeetCode problems via id

Introduction

As a world's leading online programming learning platform, LeetCode is quite popular among programmers. Since each problem has a unique number id, users tend to share problems via id. However, it is not convenient to visit problem page directly via id. People have to visit LeetCode Problems firstly, then enter that number id in the 'Search questions' input box, press 'enter', click the problem title link, finally comes to the problem page. What a hard work!

This simple project, called LCid, provides directly access to LeetCode problems via id. Features:

• Fetch all LeetCode problems via crwaler.
• Redirect to LeetCode problem page with problem id in the URL path via backend.
• Support both LeetCode global site and China site redirect.
• CI/CD, fetch all LeetCode problems daily and commit back to repository via Git Action, then trigger backend rebuild and redeploy with the latest problems via Heroku.

LCid is now available at lcid.cc. Just add / at the end of lcid.cc (e.g. lcid.cc/1), then browser will redirect you to the problem page. Simple, fast, and make your live easier.

What's more, to redirect to China site, add /cn/ instead (e.g. lcid.cc/cn/1). Interested in the brief info of the problem? Try /info/ (e.g. lcid.cc/info/1) and find more!

Environment

To start LCid on your local machine, you should have python 3.7+ installed.

The crawler is implemented with urllib3 and backend is powered with flask.

To install all those dependencies, execute pip install -r requirements.

Usage

Fetch All Problems

To fetch all problems, execute python fetch_problems_all.py. Then, you will see the logs below.

Now try get csrftoken...
Got csrftoken fakecsrftokenfakecsrftokenfakecsrftokenfakecsrftokenfakecsrftoke.
Found 2060 problems in total.
Now try fetch all 2060 LeetCode problems...
All 2060 problems fetched.
All 2060 problems info saved into problems_all.json file.

After few seconds, all problems info have been saved into problems_all.json file in json format.

Start Backend Service

To start backend service, execute python app.py (e.g. python app.py 1437). Then, the backend server will start at localhost: .

Now you can try the following endpoints. All of them should work correctly.

• localhost: /
• localhost: /1
• localhost: /cn/1
• localhost: /info/1

Deployment

To deploy the system for public access, of course, you can use any platform you like. Here, I use GitHub Actions and Heroku.

• GitHub Actions is used to fetch all LeetCode problems daily (execute python fetch_problems_all.py, get the latest problems_all.json) and commit back to repository. You would know how it works by analysing this config file.
• Heroku would rebuild and redeploy the backend service once main branch of this repository changed. This can be configured at Deploy - Automatic deploys in your Heroku app dashboard.
• Heroku also support add additional domains to visit app. Here is the official guide.

Disclaimer

• This is just a naive tool for convenient access and only call LeetCode API at low frequency. It only obtains public accessible data (no personal info or paid content collected and distributed). DO NOT ABUSE LEETCODE API!!!
• GitHub Repo: bunnyxt/lcid
• Author: bunnyxt
• License: MIT