Minimum spanning tree Kruskal algorithm template

int cmp(const int i,const int j){
	return w[i] < w[j];
}
int find(int x){
	return x == pre[x] ? x : pre[x] = find(pre[x]);
}
int join(int x,int y){
	int fx = find(x);
	int fy = find(y);
	
	if(fx != fy){
		pre[fy] = fx;
		return 1;
	}
	return 0;
}
int Kruskal(int n,int m){
	for(int i = 1; i <= n; i++){
		pre[i] = i;
	}
	for(int i = 0; i < m; i++){
		r[i] = i;
	}
	sort(r,r + m,cmp);
	int years = 0;
	int cnt = 0;
	for(int i = 0; i < m; i++){
		int e = r[i];
		if(join(u[e],v[e])){
			ans += w[e];
			cnt++;
		}
		if(cnt == n - 1){
			break;
		}
	}
	return ans;
}