hdu 4607 Park Visit (dfs)

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>
#define maxn 105000
using namespace std;

const int INF = 0x3f3f3f;

vector<int> G[maxn];
int N,M;
int maxdeep,point;
bool vis[maxn];
void dfs(int u,int deep){
if(maxdeep < deep){
maxdeep = deep;
point = u;
}
for(int i=0;i<G[u].size();i++){
int v = G[u][i];
if(!vis[v]){
vis[v] = true;   //printf("u,v  %d %d\n",u,v);jf
dfs(v,deep+1);
}
}
}

int main()
{
//if(freopen("input.txt","r",stdin)== NULL)  {printf("Error\n"); exit(0);}

int T;
cin>>T;
while(T--){
cin>>N>>M;
if(N == 1){
for(int i=1;i<=M;i++){
int K;
scanf("%d",&K);
printf("0\n");
}
continue;
}

for(int i=1;i<=N;i++)   G[i].clear();
for(int i=1;i<=N-1;i++){
int a,b;
scanf("%d %d",&a,&b);
G[a].push_back(b);
G[b].push_back(a);
}
memset(vis,0,sizeof(vis));
maxdeep = 0; point = 0;
vis[1] = true;
dfs(1,0);
memset(vis,0,sizeof(vis));
dfs(point,0);
for(int i=1;i<=M;i++){
int K;
scanf("%d",&K);
if(maxdeep >= K-1) printf("%d\n",K-1);
else           printf("%d\n",maxdeep + 2 * (K - 1 - maxdeep));
}
}
}