Poj(2560),最小生成树，Prim

#include <stdio.h>
#include <string.h>
#include <math.h>

#define INF 0x3f3f3f3f

int n;
double maps[300][300];
bool vis[300];
double dis[300];

struct Point {
double x;
double y;
}points[300];

double Prim()
{
memset(vis,false,sizeof(vis));
for(int i=1;i<=n;i++)
dis[i] = INF;

dis[1] = 0;
double ans =0;
for(int i=1;i<=n;i++)
{
double tmp = INF;
int k =0;
for(int j=1;j<=n;j++)
{
if(!vis[j]&&dis[j]<tmp)
{
tmp = dis[j];
k= j;
}
}

vis[k]=true;
ans+=tmp;
for(int i=1;i<=n;i++)
{
if(!vis[i]&&dis[i]>maps[k][i])
dis[i] = maps[k][i];
}
}
return ans;
}

int main()
{

scanf("%d",&n);
for(int i=1;i<=n;i++)
scanf("%lf%lf",&points[i].x,&points[i].y);

for(int i=1;i<=n;i++)
{
for(int j=1;j<=n;j++)
{
double x = points[i].x - points[j].x;
double y = points[i].y - points[j].y;
maps[i][j] = sqrt(x*x+y*y);
}
}
printf("%.2lf\n",Prim());

return 0;
}