https://www.luogu.com.cn/problem/P4563
https://www.luogu.com.cn/problem/P4064
https://www.luogu.com.cn/problem/P5023
武大法理学
https://codeforces.com/contest/1754/problem/E
https://codeforces.com/contest/1733/problem/D2
https://codeforces.com/gym/104077/problem/L
unix 常用命令
https://codeforces.com/contest/1736/problem/E
经济法概述
