Leetcode Difficulty Rating

Support both "leetcode.com" and "leetcode.cn".

The green/yellow/red text color is preserved, so you can still tell the official difficulty.

Problems in 1st-62nd weekly contests and problems that did not come from contests don’t have rating data and "N/A" is shown by default. You can change the setting in the extension popup.

For more details and source code, please visit:
- https://github.com/boenshao/leetcode-difficulty-rating-extension