package Algorithms;

import java.util.ArrayList;

import java.util.List;

public class Gray_Code_89 {

public static void main(String[] args) {

// TODO Auto-generated method stub

}

}

class Solution_Gray_Code_89 {

public List<Integer> grayCode(int n) {

ArrayList<Integer> set = new ArrayList<Integer>() ;

set.add(0) ;

if(n == 0) return set ;

set.add(1) ;

int posBit = 2 ;

for(int i=1; i<n; i++) {

int len = set.size() ;

System.out.println("size: " + set.size()) ;

for(int j=len-1; j>=0; j--) {

int temp_num = set.get(j) ;

set.add(temp_num|posBit) ;

}

posBit = posBit << 1 ;

}

return set ;

}

}