hdu 1011 Starship Troopers

树上的背包

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
#include <cmath>
#include <cstring>

using namespace std;

const int MAXN = 110;

int n, m;

struct Node {
    int num,cost, val;
}room[MAXN];

int  dp[MAXN][MAXN];
bool vis[MAXN];

vector<int>edge[MAXN];

void dfs(int u){
    vis[u]=1;

    if(u!=1&&edge[u].size()==1&&!room[u].cost){
        room[u].cost=1;
    }

    for (int i = room[u].cost; i <= m; i++){
        dp[u][i] = room[u].val;
    }

    for(int i=0;i<edge[u].size();i++){
        int v = edge[u][i];

        if(vis[v]) continue;

        dfs(v);

        for(int j=m ;j >= room[u].cost; j--){
            for(int k=1;k<=j-room[u].cost;k++){
                dp[u][j]=max(dp[u][j],dp[u][j-k]+dp[v][k]);
            }
        }
    }

}
int main(){
    while(scanf("%d%d",&n,&m)==2){
        if(n==-1 && m == -1) break;
        for(int i=1;i<=n;i++){
            int x;
            edge[i].clear();
            scanf("%d%d",&x,&room[i].val);
            room[i].cost = x/20 + (x%20!=0);
        }
        for(int i=1;i<n;i++){
            int a,b;
            scanf("%d%d",&a,&b);
            edge[a].push_back(b);
            edge[b].push_back(a);
        }

         if(m==0) {
            puts("0");
            continue;
         }
         memset(dp,0,sizeof(dp));
         memset(vis,0,sizeof(vis));
         dfs(1);
         printf("%d\n",dp[1][m]);
    }
}