95分，#20 WA求助

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

void out(unsigned long long  ceng,unsigned long long  num,unsigned long long  k,bool flag)
{
	if(ceng==0) return;
	unsigned long long  n=1;
	for(unsigned long long  i=1;i<=ceng-1;i++) n*=2;
	if(flag==0)
	{
		if(k>num+n)
		{
			cout<<1;
			out(ceng-1,num+n,k,1);
		}
		else
		{
			cout<<0;
			out(ceng-1,num,k,0);
		}	
	}
	else
	{
		if(k>num+n)
		{
			cout<<0;
			out(ceng-1,num+n,k,1);
		}
		else
		{
			cout<<1;
			out(ceng-1,num,k,0);
		}	
	}
}

int main()
{
	unsigned long long  n,k;
	cin>>n>>k;
	unsigned long long  num=1;
	for(unsigned long long  i=1;i<=n;i++) num*=2;
	out(n,0,k+1,0);
	
	return 0;
}