leetcode_gym/_problems/powerOfFour.md

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layout	title	last_solved	category	leetcode_url	status
page	Power of Four	2020-08-04	bit manipulation	https://leetcode.com/problems/power-of-four/	Solved

Problem

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example 1:

Input: 16
Output: true
Example 2:

Input: 5
Output: false
Follow up: Could you solve it without loops/recursion?

Solution

{% highlight python %}

def isPowerOfFour(self, num: int) -> bool:

numOnes = 0
numZerosBeforeOne = 0

while num>0:
    
    if num&1:
        numOnes+=1
    else:
        numZerosBeforeOne+=1
    
    num>>=1

if numOnes==1 and numZerosBeforeOne%2==0:
    return True
else:
    return False

{% endhighlight %}