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poj3625_i++poj3625_#include_02View Code
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;

#define maxn 1005
#define inf 0x3f3f3f3f

struct Point
{
long long x, y;
} point[maxn];

int n, m;
long double cost[maxn][maxn];
int vis[maxn];
long double lowc[maxn];

double dist(Point &a, Point &b)
{
Point p;
p.x = a.x - b.x;
p.y = a.y - b.y;
return sqrt(p.x * p.x + p.y * p.y);
}

double prim()
{
int i, j, p;
long double minc, res = 0;
memset(vis, 0, sizeof(vis));
vis[0] = 1;
for (i = 1; i < n; i++)
lowc[i] = cost[0][i];
for (i = 1; i < n; i++)
{
minc = inf;
p = -1;
for (j = 0; j < n; j++)
if (0 == vis[j] && minc > lowc[j])
{
minc = lowc[j];
p = j;
}
if (inf == minc)
return -1;
res += minc;
vis[p] = 1;
for (j = 0; j < n; j++)
if (0 == vis[j] && lowc[j] > cost[p][j])
lowc[j] = cost[p][j];
}
return res;
}

int main()
{
//freopen("t.txt", "r", stdin);
scanf("%d%d", &n, &m);
for (int i = 0; i < n; i++)
scanf("%lld%lld", &point[i].x, &point[i].y);
for (int i = 0; i < n; i++)
for (int j = i + 1; j < n; j++)
cost[i][j] = cost[j][i] = dist(point[i], point[j]);
for (int i = 0; i < m; i++)
{
int a, b;
scanf("%d%d", &a, &b);
a--;
b--;
cost[a][b] = cost[b][a] = 0;
}
printf("%.2f\n", prim());
return 0;
}