Gray Code

The gray code is a binary numeral system where two successive values differ in only one bit.

Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0.

For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:

00 - 0 01 - 1 11 - 3 10 - 2 

Note:
For a given n, a gray code sequence is not uniquely defined.

For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.

For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.

class Solution {
public:
    vector< int> grayCode( int n) {
        unsigned  int data= 0;
        
        vector< int> list;
         for( int i= 0;i<( 1<<n);i++)
            list.push_back( 0);
            
         for( int loc= 0;loc<n;loc++)
        {
             int bit= 0;
         
             int step= 1<<loc;   
             int index= 0;
             while(index<( 1<<n))
            {
                list[index]=list[index] | (bit<<loc);
                step++;
                 if(step==( 2<<loc))
                {
                    bit= 1-bit;
                    step= 0;
                }
                index++;
            }
        }
        
         return list;
    }
};