hdu 1011 Starship Troopers

来源：互联网发布：剑倚天下进阶数据最新编辑：程序博客网时间：2024/05/17 04:54

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]);    }}

0 0