Problem
An n-bit gray code sequence is a sequence of2^n integers where:
- Every integer is in the inclusive range
[0, 2^n - 1], - The first integer is
0, - An integer appears no more than once in the sequence,
- The binary representation of every pair of adjacent integers differs by exactly one bit, and
- The binary representation of the first and last integers differs by exactly one bit.
n, return any valid n-bit gray code sequence.
Examples
Constraints
1 <= n <= 16