Elimination Game Python Solution with Tests

lcpy gen -n 390   # by problem number
lcpy gen -s elimination_game   # by problem name

Input: n = 9
Output: 6
Explanation:
arr = [1, 2, 3, 4, 5, 6, 7, 8, 9]
arr = [2, 4, 6, 8]
arr = [2, 6]
arr = [6]

Input: n = 1
Output: 1

class Solution:
    # Time: O(log n)
    # Space: O(1)
    def last_remaining(self, n: int) -> int:
        head, step, left = 1, 1, True
        while n > 1:
            if left or n % 2 == 1:
                head += step
            step *= 2
            n //= 2
            left = not left
        return head