HDU 4707 Pet

http://blog.csdn.net/u014634338/article/details/42458007

#include<stdio.h>#include <vector>#include <iostream>using namespace std;const int N=100010;int n,d,cnt;vector<int>v[N];void dfs(int j,int d){    if(d<0)        cnt++;    for (int i=0; i<v[j].size(); i++)        dfs(v[j].at(i), d-1);}int main(){    int t;    scanf("%d",&t);    while (t--)    {        scanf("%d%d",&n,&d);        cnt=0;        for (int i=0; i<=n; i++)            v[i].clear();        for (int i=1; i<n; i++)        {            int a,b;            scanf("%d%d",&a,&b);            v[a].push_back(b);        }        dfs(0, d);        printf("%d\n",cnt);    }    return 0;}