【HDOJ】1561 The more, The Better

 1 /* 1561 */
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <cstring>
 5 #include <cstdlib>
 6 #include <algorithm>
 7 #include <vector>
 8 using namespace std;
 9 
10 #define MAXN 205
11 
12 vector<int> tb[MAXN];
13 int dp[MAXN][MAXN];
14 int a[MAXN];
15 int n, m;
16 
17 int max(int a, int b) {
18     return a>b ? a:b;
19 }
20 
21 void init() {
22     int i, j, k;
23     
24     for (i=0; i<=n; ++i)
25         tb[i].clear();
26     memset(dp, 0, sizeof(dp));
27 }
28 
29 void dfs(int u, int t) {
30     int i, j, k, tmp;
31     int v;
32     
33     if (t <= 0)
34         return ;
35     
36     for (i=0; i<tb[u].size(); ++i) {
37         v = tb[u][i];
38         dfs(v, t-1);
39         for (j=t; j>=1; --j) {
40             for (k=1; k<=j; ++k) {
41                 dp[u][j] = max(dp[u][j], dp[v][k]+dp[u][j-k]);
42             }
43         }
44     }
45     if (u) {
46         for (i=m; i>=1; --i)
47             dp[u][i] = dp[u][i-1] + a[u];
48     }
49 }
50 
51 int main() {
52     int i, j, k;
53     
54     #ifndef ONLINE_JUDGE
55         freopen("data.in", "r", stdin);
56     #endif
57     
58     a[0] = 0;
59     while (scanf("%d %d", &n, &m)!=EOF && (n||m)) {
60         for (i=1; i<=n; ++i) {
61             scanf("%d %d", &j, &a[i]);
62             tb[j].push_back(i);
63         }
64         dfs(0, m);
65         printf("%d\n", dp[0][m]);
66         init();
67     }
68     
69     return 0;
70 }