Today I have done leetcode's August LeetCoding Challenge with cpp.

August LeetCoding Challenge 15

Description

Power of Four

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?

Solution

class Solution {
public:
  bool isPowerOfFour(int n) {
    if(n < 1) return false;
    double p = log(n) / log(4);
    double diff = abs(p - floor(p));
    return diff < numeric_limits<double>::epsilon();  
  }
};

// Accepted
// 1063/1063 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 4.79 % of cpp submissions (8.2 MB)