POJ - 3847 Moving to Nuremberg 动归

POJ - 3847 Moving to Nuremberg

题意：一张无向有权图，包括边权和点权，求一点，使得到其他点的点权*边权之和最小

思路：

 #pragma comment(linker, "/STACK:1000000000")
 #include <iostream>
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <vector>
 #define LL long long
 #define INF 0xfffffffffffffff
 #define IN freopen("in.txt","r",stdin)
 #define OUT freopen("out.txt", "w", stdout)
 #define MAXN 50005
 using namespace std;

 struct Edge{
     int to;
     LL cost;
     Edge(int to = , LL cost = ) :to(to), cost(cost){};
 };
 Edge G[MAXN << ];
 int next[MAXN << ], head[MAXN << ];
 int e;
 void AddEdge(int from, int to, LL cost){
     e++;
     next[e] = head[from];
     head[from] = e;
     G[e].to = to;
     G[e].cost = cost;
 }
 LL g[MAXN], f[MAXN], dis[MAXN], a[MAXN];
 int cnt;
 LL ans;
 void dfs(int x, int y){
     g[x] = ;
     dis[x] = ;
     for (int i = head[x]; i != ; i = next[i]){
         Edge& e = G[i];
         if (e.to == y) continue;
         dfs(e.to, x);
         dis[x] += dis[e.to] + 2LL * e.cost * g[e.to];
         g[x] += g[e.to];
     }
     g[x] += a[x];
 }
 void work(int x, int y, LL res){
     f[x] = res;
     ans = min(f[x], ans);
     for (int i = head[x]; i != ; i = next[i]){
         Edge& e = G[i];
         if (e.to == y) continue;
         work(e.to, x, res + 2LL * e.cost * (cnt - 2LL * g[e.to]));
     }
 }
 int main()
 {
     //IN;
     int T;
     scanf("%d", &T);
     int n, m;
     while (T--){
         scanf("%d", &n);
         int x, y;
         LL z;
         memset(dis, , sizeof(dis));
         memset(head, , sizeof(head));
         memset(a, , sizeof(a));
         e = ;
         for (int i = ; i < n; i++){
             scanf("%d%d%I64d", &x, &y, &z);
             AddEdge(x, y, z);
             AddEdge(y, x, z);
         }
         scanf("%d", &m);
         cnt = ;
         for (int i = ; i <= m; i++){
             scanf("%d%d", &x, &y);
             a[x] = y;
             cnt += y;
         }
         dfs(, );
         ans = INF;
         work(, , dis[]);
         printf("%I64d\n", ans);
         for (int i = ; i <= n; i++){
             if (f[i] != ans) continue;
             printf("%d ", i);
         }
         printf("\n");

     }
     return ;
 }