[LeetCode]#342. Power of Four

Environment: Python 3.7

Key technique: Hash table

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?

Analysis:

Use Hash table to solve it without loops/recursion.

Solution:

class Solution:
    def isPowerOfFour(self, num):
        ans=[1, 4, 16, 64, 256, 1024, 4096, 16384, 65536, 262144, 1048576, 4194304, 16777216, 67108864, 268435456, 1073741824]
        return num in ans

Submitted result: