feat: add past contests

Author: yanglbme

.gitignore

@@ -4,6 +4,7 @@
 /node_modules
 /solution/result.json
 /solution/contest.json
+/solution/contest_list.json
 /solution/raw.json
 /lcof/lcof.json
 /lcof/lcof_list.json

README.md

@@ -26,6 +26,7 @@
 ## 算法全解
 
 -   [LeetCode](/solution/README.md)
+-   [往期竞赛合集](/solution/CONTEST_README.md)
 -   [剑指 Offer（第 2 版）](/lcof/README.md)
 -   [剑指 Offer（专项突击版）](/lcof2/README.md)
 -   [程序员面试金典（第 6 版）](/lcci/README.md)

README_EN.md

@@ -26,6 +26,7 @@ Complete solutions to [LeetCode](https://leetcode.com/problemset/all/), [LCOF](h
 ## Solutions
 
 -   [LeetCode](/solution/README_EN.md)
+-   [Past Contests](/solution/CONTEST_README_EN.md)
 -   [LCOF: Coding Interviews, 2nd Edition](/lcof/README_EN.md)
 -   [LCCI: Cracking the Coding Interview, 6th Edition](/lcci/README_EN.md)