异常明显的思路，考场上却不会，连确定一条边不选都没想到#include<bits/stdc++.h>usingnamespacestd;#definepiipair<int,int>#definefifirst#definesesecond#definempmake_pair#definels(rt<<1)#definers(rt<<1|1)#definemid(l+r>>1)intt,n,m