求助，样例过不了 qwq

（肯定全 WA 就不用说了 QAQ）

#include <bits/stdc++.h>

using namespace std;

int n, m;
int father[4000086];
int set_x[1000086], set_y[1000086];

struct edge {
	int u, v;
	double w;
} e[4000086];

double dist (int x1, int y1, int x2, int y2) {
	return (double)sqrt((double)(x1 - x2) * (x1 - y1) + (double)(y1 - y2) * (y1 - y2));
}

bool cmp (edge x, edge y) {
	return x.w < y.w;
}

int get (int cur) {
	if (father[cur] == cur) return cur;
	father[cur] = get(father[cur]);
	return get(father[cur]);
}

int main () {
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= n; i++)
		scanf("%d%d", &set_x[i], &set_y[i]);
	int cnt = 0;
	for (int i = 1; i <= n; i++)
		for (int j = i + 1; j <= n; j++)
			e[++cnt].u = i, e[cnt].v = j, e[cnt].w = dist(set_x[i], set_y[i], set_x[j], set_y[j]);
	for (int i = 1; i <= m; i++) {
		scanf("%d%d", &e[++cnt].u, &e[cnt].v);
		e[cnt].w = 0.0;
	}
	sort(e + 1, e + cnt + 1, cmp); 
	for (int i = 1; i <= n; i++)
		father[i] = i;
	double ans = 0.0;
	for (int i = 1; i <= cnt; i++)
		if (get(e[i].u) != get(e[i].v)) {
			father[get(e[i].u)] = e[i].v;
			ans += e[i].w;
		}
	printf("%.2f", ans);
	return 0;
}