【HDU1162】Eddy's picture（MST基础题）

很基础的点坐标MST，一不留神就AC了， - - ！！

 #include <iostream>
 #include <cstring>
 #include <cstdlib>
 #include <cstdio>
 #include <cmath>
 #include <cctype>
 #include <algorithm>
 #include <numeric>
 #include <limits.h>

 #define typec double
 using namespace std;

 const int inf = 0xffff;
 const int V = ;
 int vis[V];
 typec lowc[V], Map[V][V], point[V][];

 typec prim (typec cost[][V], int n) {
     int i, j, p;
     typec minc, res = ;
     memset(vis, , sizeof(vis));
     vis[] = ;
     for (i = ; i < n; ++ i) lowc[i] = cost[][i];
     for (i = ; i < n; ++ i) {
         minc = inf;
         p = -;
         for (j =  ; j < n; ++ j) {
             if ( == vis[j] && minc > lowc[j]) {
                 minc = lowc[j];
                 p = j;
             }
         }
         if (inf == minc) return -;
         res += minc;
         vis[p] = ;
         for (j =  ; j < n; ++ j) {
             if ( == vis[j] && lowc[j] > cost[p][j]) {
                 lowc[j] = cost[p][j];
             }
         }
     }
     return res;
 }

 double cal_dis (double x1, double y1, double x2, double y2) {
     return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
 }

 int main () {
     int n;
     while (~scanf("%d", &n)) {

         for (int i =  ; i < n; ++ i) {
             scanf("%lf %lf", &point[i][], &point[i][]);
         }

         for (int i =  ; i < V; ++ i) {
             for (int j = ; j < V; ++ j) {
                 if (i == j) Map[i][j] = ;
                 else Map[i][j] = inf;
             }
         }

         for (int i = ; i < n; ++ i) {
             for (int j = i + ; j < n; ++ j) {
                 Map[i][j] = Map[j][i] =
                     cal_dis(point[i][], point[i][], point[j][], point[j][]);
             }
         }

         //cout << prim(Map, n) << endl;
         printf("%.2lf\n", prim(Map, n));
     }
     return ;
 }