Arctic Network POJ - 2349

 1 include <stdio.h>
 2 #include <iostream>
 3 #include <queue>
 4 #include <math.h>
 5 #include <algorithm>
 6 using namespace std;
 7 
 8 const int N = (int)1e3 + 10;
 9 const int inf = (int)1e9;
10 double px[N];
11 double py[N];
12 double g[N][N];
13 double dis[N];
14 bool vis[N];
15 int s,p;
16 
17 struct node{
18     int loc;
19     double w;
20     bool friend operator<(const node & a,const node& b){
21         return a.w > b.w;
22     }
23 };
24 priority_queue<node > que;
25 
26 bool cmp(double x,double y){
27     return x > y;
28 }
29 
30 inline double dist(int a,int b){
31     return sqrt((px[a]-px[b])*(px[a]-px[b])+(py[a]-py[b])*(py[a]-py[b]));
32 }
33 
34 void build_map(){
35 
36     for(int i = 1; i <= p; i++)
37         for(int j = 1; j <= p; j++)
38             g[i][j] = g[j][i] = dist(i,j);
39 
40 }
41 
42 double prime(){
43 
44     for(int i = 1; i <= p; i++){
45         vis[i] = 0;
46         dis[i] = inf;
47     }
48 
49     while(!que.empty()) que.pop();
50 
51     que.push(node{1,0});
52     dis[1] = 0;
53 
54     while(!que.empty()){
55         int u = que.top().loc;
56         que.pop();
57         vis[u] = true;
58 
59         for(int v = 1; v <= p ;v++){
60             if(!vis[v] && dis[v] > g[u][v]){
61                 dis[v] = g[u][v];
62                 que.push(node{v,dis[v]});
63             }
64         }
65     }
66     sort(dis+1,dis+1+p,cmp);
67     /*
68     for(int i = 1; i <= p; i++)
69         printf("%lf\n",dis[i]);
70     */
71 
72 
73     return dis[s];
74 }
75 
76 int main(){
77 
78     int T;
79     scanf("%d",&T);
80 
81     while(T--){
82         scanf("%d%d",&s,&p);
83 
84         for(int i = 1; i <= p; i++)
85             scanf("%lf%lf",&px[i],&py[i]);
86 
87         build_map();
88 
89         printf("%.2f\n",prime());
90     }
91 
92     return 0;
93 }