树形dp问题（持续更新中...）

1. hdu 1561
   代码:

#include <iostream>#include <cstdio>#include <cstring>#include <vector>using namespace std;const int M = 220;int n, m, v[M];vector<int>son[M];int dp[M][M];void dfs(int num, int left){    int i, j, k, len = son[num].size();    dp[num][1] = v[num];    for (i = 0; i < len; i++)    {        if (left > 1)   dfs(son[num][i], left-1);        for (j = left; j >= 1; j--)        {            for (k = 1; k <= j; k++)            {                dp[num][j+1] = max(dp[num][j+1], dp[num][j+1-k] + dp[son[num][i]][k]);            }        }    }}int main(){#ifndef ONLINE_JUDGE    freopen("1.txt", "r", stdin);#endif    int i, j;    while(cin >>n >> m, n||m)    {        memset(v, 0, sizeof(v));        memset(dp, 0, sizeof(dp));        for (i = 0; i <= n; i++)    son[i].clear();        for (i = 1; i <= n; i++)        {            scanf("%d%d", &j, &v[i]);            son[j].push_back(i);        }        dfs(0, m+1);        printf("%d\n", dp[0][m+1]);    }    return 0;}

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