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：
1 #pragma comment(linker, "/STACK:1000000000") 2 #include <iostream> 3 #include <cstdio> 4 #include <algorithm> 5 #include <cstring> 6 #include <vector> 7 #define LL long long 8 #define INF 0xfffffffffffffff 9 #define IN freopen("in.txt","r",stdin) 10 #define OUT freopen("out.txt", "w", stdout) 11 #define MAXN 50005 12 using namespace std; 13 14 struct Edge{ 15 int to; 16 LL cost; 17 Edge(int to = 0, LL cost = 0) :to(to), cost(cost){}; 18 }; 19 Edge G[MAXN << 1]; 20 int next[MAXN << 1], head[MAXN << 1]; 21 int e; 22 void AddEdge(int from, int to, LL cost){ 23 e++; 24 next[e] = head[from]; 25 head[from] = e; 26 G[e].to = to; 27 G[e].cost = cost; 28 } 29 LL g[MAXN], f[MAXN], dis[MAXN], a[MAXN]; 30 int cnt; 31 LL ans; 32 void dfs(int x, int y){ 33 g[x] = 0; 34 dis[x] = 0; 35 for (int i = head[x]; i != 0; i = next[i]){ 36 Edge& e = G[i]; 37 if (e.to == y) continue; 38 dfs(e.to, x); 39 dis[x] += dis[e.to] + 2LL * e.cost * g[e.to]; 40 g[x] += g[e.to]; 41 } 42 g[x] += a[x]; 43 } 44 void work(int x, int y, LL res){ 45 f[x] = res; 46 ans = min(f[x], ans); 47 for (int i = head[x]; i != 0; i = next[i]){ 48 Edge& e = G[i]; 49 if (e.to == y) continue; 50 work(e.to, x, res + 2LL * e.cost * (cnt - 2LL * g[e.to])); 51 } 52 } 53 int main() 54 { 55 //IN; 56 int T; 57 scanf("%d", &T); 58 int n, m; 59 while (T--){ 60 scanf("%d", &n); 61 int x, y; 62 LL z; 63 memset(dis, 0, sizeof(dis)); 64 memset(head, 0, sizeof(head)); 65 memset(a, 0, sizeof(a)); 66 e = 0; 67 for (int i = 1; i < n; i++){ 68 scanf("%d%d%I64d", &x, &y, &z); 69 AddEdge(x, y, z); 70 AddEdge(y, x, z); 71 } 72 scanf("%d", &m); 73 cnt = 0; 74 for (int i = 1; i <= m; i++){ 75 scanf("%d%d", &x, &y); 76 a[x] = y; 77 cnt += y; 78 } 79 dfs(1, 1); 80 ans = INF; 81 work(1, 1, dis[1]); 82 printf("%I64d ", ans); 83 for (int i = 1; i <= n; i++){ 84 if (f[i] != ans) continue; 85 printf("%d ", i); 86 } 87 printf(" "); 88 89 } 90 return 0; 91 }