ZOJ1203

/*prim算法*/  
#include<stdio.h>  
#include<stdlib.h>  
#include<string.h>  
#include<math.h>  
  
  
int n;  
bool visit[111];  
double low[111];  
double distance[111][111];  
  
  
void prim(int num)  
{  
    int i, cnt = 0;  
    for(i = 0; i < n; i++)  
    {  
        if(visit[i])  
            cnt++;  
    }  
    if(cnt == n)  
        return;  
    double min = 99999999;  
    for(i = 0; i < n; i++)  
    {  
        if(!visit[i])  
            low[i] = low[i] > distance[num][i] ? distance[num][i] : low[i];  
    }  
    for(i = 0; i < n; i++)  
    {  
        if(!visit[i])  
        {  
            if(min > low[i])  
            {  
                min = low[i];  
                num = i;  
            }  
        }  
    }  
    visit[num] = 1;  
    prim(num);  
    return;  
}  
  
  
int main(void)  
{  
    int i, j, cas = 0;  
    double min;  
    double xy[111][2];  
    while(scanf("%d", &n), n)  
    {  
        min = 0;  
        memset(visit, 0, sizeof visit);  
        memset(low, 0, sizeof low);  
        memset(distance, 0, sizeof distance);  
        for(i = 0; i < n; i++)  
            scanf("%lf%lf", &xy[i][0], &xy[i][1]);  
        for(i = 0; i < n; i++)  
        {  
            for(j = 0; j < n; j++)  
                distance[i][j] = sqrt((xy[i][0] - xy[j][0]) * (xy[i][0] - xy[j][0]) + (xy[i][1] - xy[j][1]) * (xy[i][1] - xy[j][1]));  
        }  
        visit[0] = 1;  
        for(i = 0; i < n; i++)  
            low[i] = distance[0][i];  
        prim(0);  
        for(i = 0; i < n; i++)  
            min += low[i];  
        if(cas)  
            printf("\n");  
        printf("Case #%d:\nThe minimal distance is: %.2lf\n", ++cas, min);  
    }  
}