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;
    }
}; 

Gray Code,布布扣,bubuko.com

原文：http://www.cnblogs.com/erictanghu/p/3759550.html