求助，50分，第11个点开始内存MLE

#include <bits/stdc++.h>
using namespace std;
vector<string> res;
vector<string> grayCode(int n) {
	if (n == 1) {
		vector<string> one_grayCode = { "0", "1" };
		return one_grayCode;
	}
	else {
		vector<string> gray = grayCode(n - 1);
		vector<string> res;
		for (int i = 0; i < gray.size(); i++)
			res.push_back("0" + gray[i]); 
		for (int i = gray.size() - 1; i >= 0; i--)
			res.push_back("1" + gray[i]);
		return res;
	}
}
int main() {
	int n,k;
	cin>>n>>k;
	res=grayCode(n);
	cout<<res[k];
	return 0;
}