PowerOfThree

Problem

https://leetcode.com/problems/power-of-three/

Solution

Note that, if $n = 3^{x}$ , $n$ can never be negative. For positive $n ‘$ , check if $n$ is divisble by 3. If it is, divide $n$ by 3 and check again. If it is not, then $n$ is not a power of 3.

Code

https://github.com/GeorgeRPu/tech-interview-prep/blob/main/solutions/PowerOfThree.py

def isPowerOfThree(n: int) -> bool:
    """Check if ``n`` is a power of 3.
    """
    if n <= 0:
        return False
    elif n == 1:
        return True
    elif n % 3 == 0:
        return isPowerOfThree(n / 3)
    else:
        return False

Test

>>> from PowerOfThree import isPowerOfThree
>>> isPowerOfThree(27)
True
>>> isPowerOfThree(0)
False
>>> isPowerOfThree(-1)
False

Functions

isPowerOfThree(n)

Check if n is a power of 3.