题目

思路：

#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef long long ll;
#define pb push_back
#define lson p << 1
#define rson p << 1 | 1
#define fi first
#define se second
const int maxn = 1e6 + 5, maxm = 5e3 + 5;
int a[maxn], b[maxn];
int n, m;
string s;
vector<int> G[maxn];
int siz[maxn];

void dfs2(int u){
	siz[u] = 1;
	for(auto v : G[u]){
		dfs2(v);
		siz[u] += siz[v];
	}
}

int dfs(int u, int k){
	int tot = 0;
	int id = 0;
	for(auto v : G[u]){
		tot += siz[v];
		if(!id || siz[v] > siz[id]){
			id = v;
		}
	}
	if(siz[id] - k <= tot - siz[id]){
		return (tot - k) / 2;
	}
	int add &#