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Power of 2

Problem Description​

Given a non-negative integer n, the task is to check if it is a power of 2.

Examples​

Example 1:

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

Example 2:

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

Example 3:

Input: n = 3
Output: false
Explanation: 3 is not a power of 2

Your Task​

You don't need to read input or print anything. Your task is to complete the function isPowerofTwo() which takes an integer n as input and returns true if n is a power of 2, otherwise false.

Expected Time Complexity: O(1)O(1)

Expected Auxiliary Space: O(1)O(1)

Constraints​

  • 0 ≤ n ≤ 10^18

Problem Explanation​

A number is a power of 2 if there exists an integer x such that n = 2^x.

Code Implementation​

Written by @Ishitamukherjee2004
class Solution:
def isPowerofTwo(self, n: int) -> bool:
if n <= 0:
return False
# A power of two has exactly one bit set in binary representation
return (n & (n - 1)) == 0

# Example usage
if __name__ == "__main__":
solution = Solution()
print(solution.isPowerofTwo(16)) # Expected output: True
print(solution.isPowerofTwo(3)) # Expected output: False

Solution Logic:​

  1. A number n is a power of 2 if it has exactly one bit set in its binary representation.
  2. To check this, you can use the property: n & (n - 1) == 0.
  3. This expression is true only for powers of 2.

Time Complexity​

  • The function operates in constant time, O(1)O(1).

Space Complexity​

  • The function uses constant space, O(1)O(1).