delete pics to save space

7.3585.cpp

@@ -0,0 +1,58 @@
+#include<cstdio>
+#include<cstring>
+#include<algorithm>
+using namespace std;
+const int maxn=200005;
+struct Edge { int v,w; Edge *nxt; };
+Edge mem[maxn*2],*G[maxn],*ecnt;
+inline void AddEdge(int u,int v,int w) { ecnt->v=v; ecnt->w=w; ecnt->nxt=G[u]; G[u]=ecnt++; }
+int T,n,dg[maxn],d[maxn],f[maxn];
+void dp(int u,int fa)
+{
+	d[u]=0;
+	for(Edge *it=G[u];it;it=it->nxt)
+	{
+		int v=it->v,w=it->w;
+		if(v==fa) continue;
+		dp(v,u);
+		if(dg[v]==1) d[u]+=w;
+		else d[u]+=min(d[v],w);
+	}
+}
+void dfs(int u,int fa)
+{
+	for(Edge *it=G[u];it;it=it->nxt)
+	{
+		int v=it->v,w=it->w;
+		if(v==fa) continue;
+		if(dg[u]==1) f[v]=d[v]+w;
+		else f[v]=d[v]+min(f[u]-min(d[v],w),w);
+		dfs(v,u);
+	}
+}
+int main()
+{
+	#ifdef local
+	freopen("pro.in","r",stdin);
+	#endif
+	scanf("%d",&T);
+	while(T-->0)
+	{
+		scanf("%d",&n);
+		ecnt=mem;
+		memset(dg,0,sizeof(dg)); memset(G,0,sizeof(G));
+		for(int i=1;i<=n-1;i++)
+		{
+			int u,v,w; scanf("%d%d%d",&u,&v,&w);
+			AddEdge(u,v,w); AddEdge(v,u,w);
+			dg[v]++; dg[u]++;
+		}
+		dp(1,-1);
+		f[1]=d[1];
+		dfs(1,-1);
+		int res=0;
+		for(int i=1;i<=n;i++) res=max(res,f[i]);
+		printf("%d\n",res);
+	}
+	return 0;
+}