delete pics to save space

p.CH5401.cpp

@@ -0,0 +1,39 @@
+#include<cstdio>
+#include<cstring>
+#include<algorithm>
+#include<vector>
+using namespace std;
+const int maxn=6005;
+vector<int> G[maxn];
+int f[maxn][2],v[maxn],h[maxn],n;
+void dp(int u)
+{
+	f[u][0]=0;
+	f[u][1]=h[u];
+	for(int i=0;i<G[u].size();i++)
+	{
+		int v=G[u][i];
+		dp(v);
+		f[u][0]+=max(f[v][0],f[v][1]);
+		f[u][1]+=f[v][0];
+	}
+}
+int main()
+{
+	#ifdef local
+	freopen("pro.in","r",stdin);
+	#endif
+	scanf("%d",&n);
+	for(int i=1;i<=n;i++) scanf("%d",&h[i]);
+	for(int i=1;i<n;i++)
+	{
+		int x,y; scanf("%d%d",&x,&y);
+		v[x]=1;
+		G[y].push_back(x);
+	}
+	int rt;
+	for(int i=1;i<=n;i++) if(!v[i]) { rt=i; break; }
+	dp(rt);
+	printf("%d\n",max(f[rt][0],f[rt][1]));
+	return 0;
+}