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342. Power Of Four

Math Bit Manipulation Recursion

Problem - Power Of Four

Easy

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

An integer n is a power of four, if there exists an integer x such that n == 4x.

 

Example 1:

Input: n = 16
Output: true

Example 2:

Input: n = 5
Output: false

Example 3:

Input: n = 1
Output: true

 

Constraints:

  • -231 <= n <= 231 - 1

 

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

Solutions

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class Solution:
    def isPowerOfFour(self, n: int) -> bool:
        check1 = n > 0 and (n & (n - 1)) == 0 # Needs to be > 0 and check if 2^2^x
        check2 = n & 0xAAAAAAAA  == 0# bitwise and on every even number 
        return check1 and check2

Submission Stats:

  • Runtime: 0 ms (100.00%)
  • Memory: 18 MB (17.77%)