Power of Two Python Solution with Tests

Tested Python solution for LeetCode 231 with 18 pytest cases. Generate a practice environment with lcpy.

LeetCode 231, Easy. Topics: Math, Bit Manipulation, Recursion. View on LeetCode.

Generate this problem as a practice environment: tested reference solution, 18 parametrized pytest cases, and a playground notebook:

lcpy gen -n 231   # by problem number
lcpy gen -s power_of_two   # by problem name

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Problem

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

An integer n is a power of two, if there exists an integer x such that n == 2^x.

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Examples

Input: n = 1
Output: true
Explanation: 2^0 = 1

Input: n = 16
Output: true
Explanation: 2^4 = 16

Input: n = 3
Output: false

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Constraints

• -2^31 <= n <= 2^31 - 1

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

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Solution

Reference implementation from solution.py on GitHub, full suite in test_solution.py:

class Solution:
    # Time: O(1)
    # Space: O(1)
    def is_power_of_two(self, n: int) -> bool:
        return n > 0 and n & (n - 1) == 0

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Complexity

Time	Space
O(1)	O(1)

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Tags

NeetCode All.