还是GESP5级蒟蒻……

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,a[100005],ans,tmp;
vector<int>v[100005];
bool vis[100005];
void dfs(int i){
	for(auto t:v[i]){
		if(vis[t])continue;
		tmp++;
		vis[t]=true;
		dfs(t);
		vis[t]=false;
	}
}
signed main(){
	cin>>n;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1,x,y;i<n;i++){
		cin>>x>>y;
		if(x>y)v[x].push_back(y);
		else if(y>x)v[y].push_back(x);
	}
	for(int i=1;i<=n;i++,tmp=1){
		memset(vis,false,sizeof vis);
		dfs(i);
		ans=max(tmp,ans);
	}
	cout<<ans;
	return 0;
}

蒟蒻代码如上,WA+TLE,求dalao帮助!****