HDU 1162 Eddy's picture

Prim算法

#include <iostream>
#include <cstring>
#include <cmath>
int n;
double map[210][210],a[210];
int b[210];
void met(){
    int i,t=1;
    a[t]=0;
    while(b[t]==0){
        b[t]=1;
        for(i=1;i<=n;i++)
            if(b[i]==0&&a[i]>map[t][i])
                a[i]=map[t][i];
        double min=200000000;
        for(i=1;i<=n;i++)if(b[i]==0&&min>a[i])min=a[i],t=i;
    }
}
int main()
{
    int i,j,k;
    double f[210],g[210];
    while(scanf("%d",&n)!=-1){
        for(i=1;i<=n;i++)scanf("%lf%lf",&f[i],&g[i]);
        memset(map,9,sizeof(map));
        for(i=1;i<=110;i++)a[i]=200000000;
        memset(b,0,sizeof(b));
        double x,y,d;
        for(i=1;i<=n;i++){
            for(j=1;j<=i;j++){
                x=f[i]-f[j];
                y=g[i]-g[j];
                d=sqrt(x*x+y*y);
                map[i][j]=map[j][i]=d;
            }
        }met();
        double sum=0;
        for(i=1;i<=n;i++)sum+=a[i];
        printf("%.2f\n",sum);
    }
    return 0;
}