hdu 1561 树形dp

又一道树形dp，发现其实树形dp长得都挺像的。

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;

const int INF = -9999999;
const int N = 201;
int dp[N][N];
int head[N];
int value[N];
int n, m, e;

void init()
{
    e = 0;
    memset( head, -1, sizeof(head) );
}

struct Edge
{
    int v, next;
} edge[N];

void addEdge( int u, int v )
{
    edge[e].v = v;
    edge[e].next = head[u];
    head[u] = e++;
}

void dfs( int u )
{
    dp[u][1] = value[u];
    for ( int i = 2; i <= m + 1; i++ )
    {
        dp[u][i] = INF;
    }
    for ( int i = head[u]; i != -1; i = edge[i].next )
    {
        int v = edge[i].v;
        dfs(v);
        for ( int j = m + 1; j > 1; j-- )
        {
            for ( int k = 1; k < j; k++ )
            {
                dp[u][j] = max( dp[u][j], dp[u][j - k] + dp[v][k] );
            }
        }
    }
}

int main ()
{
    while ( scanf("%d%d", &n, &m) != EOF )
    {
        if ( n == 0 && m == 0 ) break;
        init();
        value[0] = 0;
        for ( int i = 1; i <= n; i++ )
        {
            int tmp;
            scanf("%d%d", &tmp, value + i);
            addEdge( tmp, i );
        }
        dfs(0);
        printf("%d
", dp[0][m + 1]);
    }
    return 0;
}