80分求助

# include <bits/stdc++.h>
using namespace std;

const int MAX = 1e5 + 7;
queue <int> q;

int head[MAX];
struct Edge {
	int to;
	int next;
} edge[MAX];
int tot = 0;

void adde(int u, int v) {
	tot++;
	edge[tot].to = v;
	edge[tot].next = head[u];
	head[u] = tot;
}
int n, m;
int ans[MAX], ind[MAX];

void bfs() {
	while(!q.empty()) {
		int u = q.front();
		q.pop();
		for(int i = head[u]; i ; i = edge[i].next) {
			int v = edge[i].to;
			ans[v] = ans[u] + 1;
			ind[v]--;
			if(ind[v] == 0) q.push(v);	
		}
	}
}
int main() {
	cin>>n>>m;
	for(int i = 1; i <= m; i++) {
		int u, v;
		cin>>u>>v;
		adde(u, v);
		ind[v]++;
	} 
	for(int i = 1; i <= n; i++) {
		if(ind[i] == 0) {
			ans[i] = 1;
			q.push(i);
		}
	}
	bfs();
	for(int i = 1; i <= n; i++) cout<<ans[i]<<endl;
		
}