麻了，数据范围是1e4

#include<bits/stdc++.h>
using namespace std;
#define ioio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
typedef long long ll;
const double eps = 5e4 - 6;
const int INF = 0x3f3f3f3f;
const int N = 1e4 + 7;

int fa[N];
int n, e, len = 1;
int ma[N][N];
struct st {
	int a, b, k;
} pre[N];
int cmp(st a, st b) {
	return a.k < b.k;
}
void init() {
	for (int i = 0; i <= n; i++)
		fa[i] = i;
}
int find(int x) {
	if (x != fa[x])
		fa[x] = find(fa[x]);
	return fa[x];
}
void kru() {
	int ans = 0;
	for (int i = 1; i <= len; i++) {
		int u = pre[i].a;
		int v = pre[i].b;
		int w = pre[i].k;
		int uu = find(u);
		int vv = find(v);
		if (uu != vv) {
			fa[vv] = uu;
			ans += w;
		}
	}
	printf("%d\n", ans);
}
void mer(int a, int b) {
	int x = find(a);
	int y = find(b);
	if (x != y)
		fa[x] = y;
}
int main() {
	scanf("%d", &n);
	init();
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= n; j++) {
			scanf("%d", &ma[i][j]);
			pre[len].a = i, pre[len].b = j, pre[len].k = ma[i][j];
			len++;
		}
	sort(pre + 1, pre + len + 1, cmp);
	kru();
	return 0;
}