Given an integer `n`, return `true` if it is a power of three. Otherwise, return `false`.

An integer `n` is a power of three, if there exists an integer `x` such that `n == 3x`.

Example 1:

    Input: n = 27
    Output: true

Example 2:

    Input: n = 0
    Output: false

Example 3:

    Input: n = 9
    Output: true

Constraints:

- `-231 <= n <= 231 - 1`

Follow up: Could you solve it without loops/recursion?