HDU 1561 依赖背包

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

const int N = 210;
int n,m;
int head[N],son[N];
int w[N];
int dp[N][N];

int max(int a,int b) {return a > b ? a : b;}

int dfs(int fa)
{
    int i,j,k;
    int tot = 1;
    dp[fa][1] = w[fa];
    for(i = son[fa]; i != -1; i = head[i])
    {
        tot += dfs(i);  //剪枝，每次只用循环到当前能达到的最大值。 
        for(j = tot; j >= 1; j--)
            for(k = 1; k+j <= tot+1; k++)
                dp[fa][j+k] = max(dp[fa][j+k],dp[fa][j]+dp[i][k]);
    }
    return tot;
}

int main()
{
    int i,k;
    while(scanf("%d%d",&n,&m),n+m)
    {
        memset(son,-1,sizeof(son));
        w[0] = 0;
        for(i = 1; i <= n; i++) 
        {
            scanf("%d%d",&j,w+i);
            head[i] = son[j];
            son[j] = i;
        }
        memset(dp,sizeof(dp));
        dfs(0);
        printf("%d\n",dp[0][m+1]);
    }
    return 0;
}

#include <stdio.h>
#include <string.h>

#define MAX 210

#define max(a,b) (a)>(b) ? (a) : (b)


struct node {
        int v;
        node *next;
}*head[MAX],tree[MAX];

int n,m,money[MAX];
int ptr,dp[MAX][MAX];


void Initial() {
        ptr = 1;
        memset(dp,sizeof(dp));
        memset(head,NULL,sizeof(head));
}

void AddEdge(int fa,int son) {
        tree[ptr].v = son;
        tree[ptr].next = head[fa];
        head[fa] = &tree[ptr++];
}

int Tree_DP(int v) {

        int i,k,tot = 1;
        node *p = head[v];

        while (p != NULL) {

                tot += Tree_DP(p->v);
                int tp = tot < m ? tot : m; //加个剪枝，这个到目前为止能到达最大容量
                for (j = tp; j >= 1; --j) //分组背包
                        for (i = 1; i <= j; ++i)
                                dp[v][j] = max(dp[v][j],dp[p->v][i]+dp[v][j-i]);
                p = p->next;
        }

        if (v != 0) {
                for (j = m; j >= 1; --j)
                        dp[v][j] = dp[v][j-1] + money[v]; //必选当前节点自己
        }
        return tot;
}


int main()
{
        int i,a,b;
        while (scanf("%d%d",n+m) {
                Initial();
                for (i = 1; i <= n; ++i) {
                        scanf("%d%d",&a,&b);
                        money[i] = b;
                        AddEdge(a,i);
                }
                Tree_DP(0);
                printf("%d\n",dp[0][m]);
        }
}