[ABC284C] Count Connected Components
rt 此题总是RE，大神帮忙看看

#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e4;
int n,m,p[N + 5];
int u,v,ans;
int _find(int x){
	if(p[x] != x) return _find(p[x]);
	else p[x];
}
	
void _make(int x,int y){
	p[_find(x)] = _find(y);
}
signed main(){
	cin >> n >> m;
	for(int i = 1 ; i <= n ; i ++) p[i] = i;
	for(int i = 1 ; i <= m ; i ++){
		cin >> u >> v;
		_make(u,v);
	}
	ans = n;
	for(int i = 1 ; i <= n ; i ++)
		if(p[i] != i) ans --;
	cout << ans << endl;
	return 0;
}

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