hdu1520 树形dp

每个节点有权值，子节点和父节点不能同时选，问最后能选的最大价值是多少？

#include<cstdio>
#include<algorithm>
#include<vector>
#include<queue>
#include<cmath>
#include<cstring>
using namespace std;

typedef long long int64;
const int INF = 0x3f3f3f3f;
const double PI  = acos(-1.0);

const int MAXN = 6010;

vector<int>adj[MAXN];
int indeg[MAXN];
int val[MAXN];
int f[MAXN][2];
int n, m;

void dfs(int u){
    f[u][0] = 0;
    f[u][1] = val[u];
    for(int i=0; i<adj[u].size(); ++i){
        int v = adj[u][i];
//        if(vis[v]) continue;
        dfs(v);
        f[u][0] += max(f[v][1], f[v][0]);
        f[u][1] += f[v][0];
    }
}

int main(){
    
    while(~scanf("%d", &n) && n){
        
        for(int i=1; i<=n; ++i) adj[i].clear();
        
        for(int i=1; i<=n; ++i)
            scanf("%d", &val[i]);
        
        memset(indeg, 0, sizeof(indeg));
        
        int u, v;
        while(~scanf("%d%d", &v, &u) && v+u){
            adj[u].push_back(v);
            ++indeg[v];
        }
        
        memset(f, 0, sizeof(f));
        for(int i=1; i<=n; ++i)if(!indeg[i]){
            dfs(i);
            printf("%d\n", max(f[i][0], f[i][1]));
            break;
        }
    }
    
    return 0;
}

原文：http://blog.csdn.net/fangpinlei/article/details/45418967