Problem
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:
-2^31 <= n <= 2^31 - 1
Follow up: Could you solve it without loops/recursion?
Solution
/**
* @param {number} n
* @return {boolean}
*/
var isPowerOfFour = function(n) {
if (n === 0) {
return false;
} else if (n === 1) {
return true;
} else if (!Number.isInteger(n/4)) {
return false;
} else {
return isPowerOfFour(n/4)
}
};
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).