HDU 1561 The more, The Better

樹形dp。卡了下。一開始是在一條鏈上做dp,當1爲根節點，2,3都是其子節點時，我的做法無法同時選1,2,3。dp第一位代表節點，第二維代表用掉數目，由下一層節點遞歸上來。ps:改掉了波神吐槽的指針。。。

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <cmath>
using namespace std;
typedef long long LL;
#define INF 1000000007
#define N 2005
int n, m;
struct Node{
    int v;
    int next;
}e[N];
int ptr;
int head[N];
int val[N];
int dp[205][205];
void init(){
    memset(head, -1, sizeof(head));
    memset(val, 0, sizeof(val));
    memset(dp, 0, sizeof(dp));
    ptr = 0;
}
void adde(int x, int y){
    e[ptr].v = x;
    e[ptr].next = head[y];
    head[y] = ptr++;
    e[ptr].v = y;
    e[ptr].next = head[x];
    head[x] = ptr++;
}
void tdp(int rt, int par){
    int p = head[rt];
    for(int p = head[rt]; p != -1; p = e[p].next){
        if(e[p].v != par){
            tdp(e[p].v, rt);
            for(int i = m; i >= 0; i--){
                for(int j = 0; j <= i; j++){
                    dp[rt][i] = max(dp[rt][i], dp[e[p].v][j] + dp[rt][i - j]);
                }
            }
        }
    }
    if(rt != 0){
        for(int i = m; i > 0; i--)
            dp[rt][i] = dp[rt][i - 1] + val[rt];
    }
}
int main(){
    while(scanf("%d%d", &n, &m), n || m){
        init();
        int x, y;
        for(int i = 1; i <= n; i++){
            scanf("%d%d", &x, &y);
            adde(i, x);
            val[i] = y;
        }
        tdp(0, -1);
        printf("%d\n", dp[0][m]);
    }
    return 0;
}