树上dp
https://codeforces.com/gym/103119/problem/I
https://codeforces.com/gym/103447/problem/C
https://codeforces.com/gym/103446/problem/G
https://codeforces.com/gym/104008/problem/G
杂
https://codeforces.com/gym/103729/problem/L segmenttree
https://codeforces.com/gym/103729/problem/J
https://codeforces.com/gym/103729/problem/C
https://codeforces.com/gym/103729/problem/F
https://codeforces.com/gym/103729/problem/A
https://codeforces.com/gym/103729/problem/E
https://codeforces.com/contest/1701
https://acm.hdu.edu.cn/showproblem.php?pid=6989
https://atcoder.jp/contests/abc248/tasks/abc248_g