uva 10034

计算所有点之间的权值   然后就是最小生成树 

#include<cstring>
#include<string>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<map>
#include<deque>
using namespace std;
struct point
{
    double x,y;
};
struct edge
{
    int u,v;
    double w;
    void f(int i, int j, double k)
    {
        u = i;
        v = j;
        w = k;
    }
    bool operator < (const edge &a) const
    {
        return w < a.w;
    }
};
edge e[10001];
point p[101];
int f[101];
int n, l;
int find2(int x)
{
    return f[x] == x ? x : f[x] = find2(f[x]);
}
double solve()
{
    for(int i = 0; i < n; i++)
        f[i] = i;
    double s = 0;
    for(int i = 0; i < l; i++)
    {
        int a = find2(e[i].u), b = find2(e[i].v);
        if(a != b)
        {
            f[a] = b;
            s += e[i].w;
        }
    }
    return s;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d",&n);
        for(int i = 0; i < n; i++)
        {
            scanf("%lf%lf",&p[i].x,&p[i].y);
        }
        l = 0;
        for(int i = 0; i < n; i++)
            for(int j = i+1; j < n; j++)
            {
                e[l++].f(i, j, sqrt((p[i].x-p[j].x)*(p[i].x-p[j].x)+(p[i].y-p[j].y)*(p[i].y-p[j].y)));
            }
        sort(e,e+l);
        printf("%.2lf\n",solve());
        if(t)
            puts("");
    }
}