LeetCode: Gray Code

LeetCode: 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:

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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.

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public class GrayCode {
    private static final Logger log = Logger.getLogger(GrayCode.class);
    public List<Integer> grayCode(int n) {
        List<Integer> result = new ArrayList<Integer>();
        result.add(0);
        for (int i = 0; i < n; i++) {
            int inc = 1 << i;
            for (int j = result.size() - 1; j >= 0; j--) {
                result.add(result.get(j) + inc);
            }
        }
        return result;
    }
}