Question

Given an integer (signed 32 bits), write a function to check whether it is a power of 4.

Example 1:

Input: 16 Output: true

Example 2:

Input: 5 Output: false

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

Difficulty:Easy

Category:Bit-Manipulation

Analyze

Solution

class Solution {
 public:
  bool isPowerOfFour(int num) {
    int temp = 0b01010101010101010101010101010101;
    return num > 0 && (num & (num - 1)) == 0 && (num & temp) != 0;
  }
};