Power of Two

Description

Given an integer, write a function to determine if it is a power of two.

Example 1:

Input: 1
Output: true 
Explanation: 20 = 1

Example 2:

Input: 16
Output: true
Explanation: 24 = 16

Example 3:

Input: 218
Output: false

Solution(javascript)

// 1: 除法
// const isPowerOfTwo = (n) => {
//   while (n > 1) {
//     n /= 2
//   }
//   return n === 1
// }

// 2: bit manipulation
const isPowerOfTwo = (x) => {
  if (x <= 0) {
    return false
  }
  return (x & (x - 1)) === 0
}