莫名奇妙就A了

#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
template<typename T>void re(T&x){
	x = 0; int sign = 1; char c;
	do{c = getchar(); if (c == '-') sign = -1;}while(!isdigit(c));
	do{x = x * 10 + c - '0'; c = getchar();}while(isdigit(c));
	x *= sign;
}
const int N = 2e5 + 1000;
int n, m;
vector<ll> v[N];
queue<ll> q;
ll dist[N];
int main(){
	re(n), re(m);
	int x, y;
	for (int i = 1; i <= m; i ++){
		re(x), re(y);
		v[y].push_back(x);
	}
	for (int i = n; i >= 1; i --){
		if (!dist[i]){
			q.push(i);
			while (!q.empty()){
				ll x = q.front(); q.pop();
				if (dist[x]) continue;
				if (!dist[x])
					dist[x] = i;
				for (int i = 0; i < v[x].size(); i ++){
					q.push(v[x][i]);
				}
			}
			while (q.size()) q.pop();
		}
	}
	for (int i = 1; i <= n; i ++){
		printf("%lld ", dist[i]);
	}
	return 0;
}