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342. Power of Four

Description

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

An integer n is a power of four, if there exists an integer x such that n == 4x.

 

Example 1:

Input: n = 16
Output: true

Example 2:

Input: n = 5
Output: false

Example 3:

Input: n = 1
Output: true

 

Constraints:

  • -231 <= n <= 231 - 1

 

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

Solutions

  • class Solution {
        public boolean isPowerOfFour(int n) {
            return n > 0 && (n & (n - 1)) == 0 && (n & 0xaaaaaaaa) == 0;
        }
    }
    
  • class Solution {
    public:
        bool isPowerOfFour(int n) {
            return n > 0 && (n & (n - 1)) == 0 && (n & 0xaaaaaaaa) == 0;
        }
    };
    
  • class Solution:
        def isPowerOfFour(self, n: int) -> bool:
            return n > 0 and (n & (n - 1)) == 0 and (n & 0xAAAAAAAA) == 0
    
    
  • func isPowerOfFour(n int) bool {
    	return n > 0 && (n&(n-1)) == 0 && (n&0xaaaaaaaa) == 0
    }
    
  • function isPowerOfFour(n: number): boolean {
        return n > 0 && (n & (n - 1)) == 0 && (n & 0xaaaaaaaa) == 0;
    }
    
    
  • /**
     * @param {number} n
     * @return {boolean}
     */
    var isPowerOfFour = function (n) {
        return n > 0 && (n & (n - 1)) == 0 && (n & 0xaaaaaaaa) == 0;
    };
    
    

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