231. Power of Two

LeetCode 231. Power of Two

Description

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 == 2x.

Example 1:

Input: n = 1
Output: true
Explanation: 20 = 1

Example 2:

Input: n = 16
Output: true
Explanation: 24 = 16

Example 3:

Input: n = 3
Output: false

Constraints:

• -2^31 <= n <= 2^31 - 1

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

Tags

Math, Bit Manipulation

Solution

The positive number n is a power of 2 if and only if it meets n&(n-1) == 0.

Complexity

• Time complexity: $O(1)$

• Space complexity: $O(1)$

Code

func isPowerOfTwo(n int) bool {
	return n > 0 && n&(n-1) == 0
}