思路：dfs递归解决

#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ULL;
void dfs(int n,ULL k){
	if(n <= 0)return ;
	if(n == 1)
    {
		if(k == 0)
			printf("0");
		else printf("1");
		return ;
	}
	ULL x = ULL(pow(2 , n - 1));
	if(k < x)
    {
		printf("0");
		dfs(n - 1,k);
	} 
	else
    {
		printf("1");
		dfs(n - 1,x - 1 - k + x);
	}
	return ;
}
int main(){
    //freopen("code.in","r",stdin);
    //freopen("code.out","w",stdout);
	int n;
	ULL k;
	scanf("%d%llu",&n,&k);
	dfs(n , k);
	return 0;
}