hdu 5326 dfs

多校签到题，dfs一下就好了。
 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 using namespace std;
 5 
 6 const int N = 101;
 7 int head[N];
 8 int sum[N];
 9 bool f[N];
10 int n, k, e;
11 
12 struct Edge 
13 {
14     int v, next;
15 } edge[N];
16 
17 void addEdge( int u, int v )
18 {
19     edge[e].v = v;
20     edge[e].next = head[u];
21     head[u] = e++;
22 }
23 
24 void dfs( int u )
25 {
26     sum[u] = 1;
27     for ( int i = head[u]; i != -1; i = edge[i].next )
28     {
29         int v = edge[i].v;
30         dfs(v);
31         sum[u] += sum[v];
32     }
33 }
34 
35 int main()
36 {
37     while ( scanf("%d%d", &n, &k) != EOF )
38     {
39         e = 0;
40         memset( head, -1, sizeof(head) );
41         memset( f, 0, sizeof(f) );
42         for ( int i = 1; i < n; i++ )
43         {
44             int u, v;
45             scanf("%d%d", &u, &v);
46             addEdge( u, v );
47             f[v] = 1;
48         }
49         int root;
50         for ( int i = 1; i <= n; i++ )
51         {
52             if ( !f[i] )
53             {
54                 root = i;
55                 break;
56             }
57         }
58         dfs(root);
59         int cnt = 0;
60         for ( int i = 1; i <= n; i++ )
61         {
62             if ( sum[i] == k + 1 )
63             {
64                 cnt++;
65             }
66         }
67         printf("%d
", cnt);
68     }
69     return 0;
70 }