codeforce 580C 简单深搜

如果说要A和B相连，要把这个图储存，那么用到vector 数组，如果没有权，直接vectorG[maxn];G[x]push_back(y);G[y].push_back(x).如果有权，先定义一个结构体数组，vector《node>G[maxn];G[x].push_back(node(y,cost);G[y].push_baxk(node(x,cost);

#include <stdio.h>
#include <iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cstring>
using namespace std;

const int maxn = 2e5;
int m,n;
int a[maxn];
 int ans;  
int vis[maxn];

vector<int>G[maxn];

int dfs(int cur,int sum)
{
    vis[cur] = 1;
    if(sum > n)
    return 0;
   int flag = 0;
    for(int i = 0; i < G[cur].size(); i++)
    {
        int v = G[cur][i];
        if(vis[v] == 0)
        {
            flag = 1;
            if(a[v] == 1)
                dfs(v,sum+a[v]);
            else
                dfs(v,0);
        }
    }
    if(flag == 0)
        ans++;
}

int main()
{
    while(scanf("%d%d",&m,&n)!=EOF)
    {
        memset(vis,0,sizeof(vis));
        for(int i = 1; i <= m; i++)
        {    G[i].clear();
            scanf("%d",&a[i]);
        }
        for(int i = 1; i < m; i++)
        {
            int x,y;
            scanf("%d%d",&x,&y);
            G[x].push_back(y);
            G[y].push_back(x);
        }
        ans = 0;
        dfs(1,a[1]);
        printf("%d\n",ans);
    }
    return 0;
}