HDU 1561 The more, The Better

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 210;
18 struct arc{
19     int to,next;
20     arc(int x = 0,int y = -1){
21         to = x;
22         next = y;
23     }
24 };
25 arc e[maxn*maxn];
26 int dp[maxn][maxn],head[maxn],val[maxn],n,m,tot;
27 bool vis[maxn];
28 void add(int u,int v){
29     e[tot] = arc(v,head[u]);
30     head[u] = tot++;
31 }
32 void dfs(int u){
33     vis[u] = true;
34     dp[u][1] = val[u];
35     for(int i = head[u]; ~i; i = e[i].next){
36         if(vis[e[i].to]) continue;
37         dfs(e[i].to);
38         for(int j = m+1; j >= 1; j--){
39             for(int k = 1; k < j; ++k)
40                 dp[u][j] = max(dp[u][j],dp[u][j-k] + dp[e[i].to][k]);
41         }
42     }
43 }
44 int main() {
45     int u,v;
46     while(scanf("%d %d",&n,&m),n||m){
47         memset(head,-1,sizeof(head));
48         memset(vis,false,sizeof(vis));
49         for(int i = 1; i <= n; ++i){
50             scanf("%d %d",&u,val+i);
51             add(u,i);
52         }
53         memset(dp,0,sizeof(dp));
54         dfs(0);
55         printf("%d\n",dp[0][m+1]);
56     }
57     return 0;
58 }