https://acm.hdu.edu.cn/showproblem.php?pid=7191
https://ac.nowcoder.com/acm/contest/38727/B
https://acm.hdu.edu.cn/showproblem.php?pid=7206
https://codeforces.com/contest/1614/problem/D2
https://codeforces.com/gym/104160/problem/G
SAM概述
LCT概述
https://www.luogu.com.cn/problem/P3953
https://www.luogu.com.cn/problem/P2605
https://atcoder.jp/contests/nikkei2019-qual
