89. 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.

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bit

 

public class Solution {
    public ArrayList<Integer> grayCode(int n) {
        
        ArrayList<Integer> rst = new ArrayList<Integer>();
        int count = 1 << n;
        
        for(int i=0; i<count;i++){
            rst.add(i ^ (i>>1));
        }
        
        return rst;
        
    }
}