https://vjudge.net/contest/218179#problem/F
https://vjudge.net/contest/218179#problem/J
https://vjudge.net/contest/218179#problem/M
https://vjudge.net/contest/218179#status/xiayuyang/P/0/
https://vjudge.net/contest/282940#problem/I
贪心题，比较复杂
原文：https://www.cnblogs.com/downrainsun/p/10651442.html