56 lines
838 B
Markdown
56 lines
838 B
Markdown
---
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layout: page
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title: Power of Four
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last_solved: 2020-08-04
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category: bit manipulation
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leetcode_url: https://leetcode.com/problems/power-of-four/
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status: Solved
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---
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Problem
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-------
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```
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Given an integer (signed 32 bits), write a function to check whether it is a power of 4.
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Example 1:
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Input: 16
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Output: true
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Example 2:
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Input: 5
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Output: false
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Follow up: Could you solve it without loops/recursion?
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```
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Solution
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----------
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{% highlight python %}
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def isPowerOfFour(self, num: int) -> bool:
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numOnes = 0
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numZerosBeforeOne = 0
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while num>0:
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if num&1:
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numOnes+=1
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else:
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numZerosBeforeOne+=1
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num>>=1
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if numOnes==1 and numZerosBeforeOne%2==0:
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return True
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else:
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return False
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{% endhighlight %}
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![image1]() |