delete pics to save space

1.1131.cpp

@@ -0,0 +1,38 @@
+#include<cstdio>
+#include<vector>
+#include<algorithm>
+using namespace std;
+const int maxn=500005;
+int n,s; long long res;
+vector<int> G[maxn],V[maxn];
+int dfs(int u,int fa)
+{
+	int maxv=0;
+	vector<int> dep;
+	for(int i=0;i<G[u].size();i++)
+	{
+		int v=G[u][i];
+		if(v==fa) continue;
+		int w=dfs(v,u)+V[u][i];
+		maxv=max(maxv,w);
+		dep.push_back(w);
+	}
+	for(int i=0;i<dep.size();i++) res+=maxv-dep[i];
+	return maxv;
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	scanf("%d%d",&n,&s);
+	for(int i=0;i<n-1;i++)
+	{
+		int a,b,c; scanf("%d%d%d",&a,&b,&c);
+		G[a].push_back(b); G[b].push_back(a);
+		V[a].push_back(c); V[b].push_back(c);
+	}
+	dfs(s,-1);
+	printf("%lld\n",res);
+	return 0;
+}