POJ 1155 TELE

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 using namespace std;
 5 const int maxn = 3005;
 6 const int INF = 0x3f3f3f3f;
 7 int dp[maxn][maxn],cnt[maxn],val[maxn],n,m;
 8 struct arc{
 9     int to,w,next;
10     arc(int x = 0,int y = 0,int z = -1){
11         to = x;
12         w = y;
13         next = z;
14     }
15 }e[maxn<<1];
16 int head[maxn],tot;
17 void add(int u,int v,int w){
18     e[tot] = arc(v,w,head[u]);
19     head[u] = tot++;
20 }
21 void dfs(int u){
22     cnt[u] = 1;
23     for(int i = 1; i <= m; ++i)
24         dp[u][i] = -INF;
25     dp[u][0] = 0;
26     if(head[u] == -1){
27         dp[u][1] = val[u];
28         return;
29     }
30     for(int i = head[u]; ~i; i = e[i].next){
31         dfs(e[i].to);
32         cnt[u] += cnt[e[i].to];
33         for(int j = cnt[u]; j >= 1; --j){
34             for(int k = 0; k < j; ++k)
35                 dp[u][j] = max(dp[u][j],dp[u][k]+dp[e[i].to][j-k]-e[i].w);
36         }
37      }
38 }
39 int main(){
40     int v,w,k;
41     while(~scanf("%d %d",&n,&m)){
42         memset(head,-1,sizeof head);
43         for(int i = 1; i <= n - m; ++i){
44             scanf("%d",&k);
45             while(k--){
46                 scanf("%d %d",&v,&w);
47                 add(i,v,w);
48             }
49         }
50         for(int i = n - m + 1; i <= n; ++i)
51             scanf("%d",val+i);
52         dfs(1);
53         int ans = 0;
54         for(int i = m; i >= 1; --i)
55         if(dp[1][i] >= 0) {
56             ans = i;
57             break;
58         }
59         printf("%d\n",ans);
60     }
61     return 0;
62 }