hdu 1162 Eddy's picture（最小生成树）

/*水、模板题*/

#include<cstring>

#include<cstdio>

#include<cmath>

#define INF 1<<30

double map[130][130],low[130],a[110],b[110];

int vis[130];

int n;

double dis(int i,int j)

{

return sqrt((a[i]-a[j])*(a[i]-a[j])+(b[i]-b[j])*(b[i]-b[j]));

}

double prim()

{

double ans=0;

for(int i = 0; i <= n; i++)

low[i] = map[0][i];

vis[0] = 1;

for(int i = 1; i < n; i++)

{

int temp = INF,pos=-1;

for(int j = 0; j < n; j++)

if(!vis[j]&&temp>low[j])

{

temp=low[j];

pos = j;

}

vis[pos] = 1;

ans += low[pos];

for(int j = 0; j < n; j++)

if(!vis[j]&&low[j]>map[pos][j])

low[j] = map[pos][j];

}

return ans;

}

int main()

{

while(scanf("%d",&n)==1)

{

memset(vis,0,sizeof(vis));

for(int i = 0; i < n; i++)

for(int j = 0; j < n; j++)

map[i][j] = INF;

for(int i = 0; i < n; i++)

{

scanf("%lf %lf",&a[i],&b[i]);

}

for(int i = 0; i < n; i++)

for(int j = i+1; j < n; j++)

map[i][j] = map[j][i] = dis(i,j);

printf("%.2lf\n",prim());

}

return 0;

}