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;}
，人生不如意十之八-九，与其诅咒黑暗，倒不如在生命中点燃一盏灯
