还是畅通工程 HDU - 1233

题目链接：https://vjudge.net/problem/HDU-1233

思路：

最小生成树板子。

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <queue>
 4 using namespace std;
 5 
 6 const int N = 110;
 7 const int inf = (int)1e9;
 8 int g[N][N];
 9 bool vis[N];
10 int dis[N];
11 struct node{
12     int loc;
13     int w;
14 
15     bool friend operator<(const node& a,const node& b){
16         return a.w > b.w;
17     }
18 };
19 priority_queue<node > que;
20 
21 void init(int& n){
22 
23     for(int i = 1; i <= n; i++){
24 
25         dis[i] = inf;
26         vis[i] = 0;
27         for(int j = 1; j <= n; j++)
28             if(i == j) g[i][j] = 0;
29             else g[i][j] = inf;
30     }
31 
32 }
33 
34 int prime(int& n){
35 
36     while(!que.empty()) que.pop();
37 
38     que.push(node{1,0});
39     dis[1] = 0;
40 
41     int u;
42     while(!que.empty()){
43         u = que.top().loc;
44         que.pop();
45         vis[u] = 1;
46 
47         for(int v = 1; v <= n; v++){
48             if(!vis[v] && dis[v] > g[u][v]){
49                 dis[v] = g[u][v];
50                 que.push(node{v,dis[v]});
51             }
52         }
53     }
54 
55     int ans = 0;
56     for(int i = 1; i <= n; i++) ans += dis[i];
57     return ans;
58 }
59 
60 int main(){
61 
62     int n;
63     while(~scanf("%d",&n) && n){
64 
65         int u,v,w;
66         int len = n*(n-1)/2;
67 
68         init(n);
69 
70         for(int i = 1; i <= len; i++){
71             scanf("%d%d%d",&u,&v,&w);
72 
73             if(g[u][v] > w)
74                 g[u][v] = g[v][u] = w;
75         }
76 
77         printf("%d\n",prime(n));
78     }
79 
80 
81     return 0;
82 }