hdu 5326 dfs

多校签到题，dfs一下就好了。

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

const int N = 101;
int head[N];
int sum[N];
bool f[N];
int n, k, e;

struct Edge 
{
    int v, next;
} edge[N];

void addEdge( int u, int v )
{
    edge[e].v = v;
    edge[e].next = head[u];
    head[u] = e++;
}

void dfs( int u )
{
    sum[u] = 1;
    for ( int i = head[u]; i != -1; i = edge[i].next )
    {
        int v = edge[i].v;
        dfs(v);
        sum[u] += sum[v];
    }
}

int main()
{
    while ( scanf("%d%d", &n, &k) != EOF )
    {
        e = 0;
        memset( head, -1, sizeof(head) );
        memset( f, 0, sizeof(f) );
        for ( int i = 1; i < n; i++ )
        {
            int u, v;
            scanf("%d%d", &u, &v);
            addEdge( u, v );
            f[v] = 1;
        }
        int root;
        for ( int i = 1; i <= n; i++ )
        {
            if ( !f[i] )
            {
                root = i;
                break;
            }
        }
        dfs(root);
        int cnt = 0;
        for ( int i = 1; i <= n; i++ )
        {
            if ( sum[i] == k + 1 )
            {
                cnt++;
            }
        }
        printf("%d
", cnt);
    }
    return 0;
}