样例过了但WA一片

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<queue>
#include<vector>
#include<cstring>
using namespace std;
int n,m;
vector<int>p[100005];
queue<int>q;
bool book[100005];
void dfs(int x)
{
	cout<<x<<" ";
	for(int i=0,sz=p[x].size();i<sz;i++)
	{
		if(!book[p[x][i]])
		{
			book[p[x][i]]=1;
			dfs(p[x][i]);
		}
	}
}

int main()
{
	cin>>n>>m;
	for(int i=1;i<=m;i++)
	{
		int x,y;
		cin>>x>>y;
		p[x].push_back(y);
	}
	book[1]=true;
	dfs(1);
	memset(book,false,sizeof(book));
	cout<<endl;
	book[1]=true;
	q.push(1);
	while(!q.empty())
	{
		int k=q.front();
		q.pop();
		cout<<k<<" ";
		for(int i=0,sz=p[k].size();i<sz;i++)
		{
			if(!book[p[k][i]])
		    {
			    book[p[k][i]]=1;
			    q.push(p[k][i]);
		    }
		}
	}
	return 0;
}