Power of Four

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

A number is a power of four if there exists an integer x such that n === 4^x.

Examples

Input: n = 1
Output: true
Explanation: 4^0 = 1

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

Input: n = 8
Output: false
Explanation: 8 is not a power of 4

Input: n = 0
Output: false
Explanation: 0 is not a power of 4

Constraints

• (-2^{31} \leq n \leq 2^{31} - 1)
• Return false for:
  • n ≤ 0
  • Non-integer inputs

Function Signature

function isPowerOfFour(n) {
  // Your code here
}

Test Cases

Base cases:

• n = 1
• n = 4
• n = 0

Powers of 4:

• n = 16
• n = 64
• n = 256
• n = 1024

Non-powers:

• n = 2
• n = 8
• n = 32
• n = 100

Edge cases:

• n = 0
• n = -4
• n = -1

Large numbers:

• n = 4^15
• n = 4^16 - 1