Given an integer n, return true if it is a power of three. Otherwise, return false.
An integer n is a power of three, if there exists an integer x such that n == 3x.
Example 1:
Input: n = 27
Output: true
Explanation: 27 = 33
Example 2:
Input: n = 0
Output: false
Explanation: There is no x where 3x = 0.
Example 3:
Input: n = -1
Output: false
Explanation: There is no x where 3x = (-1).
Constraints:
- -231 <= n <= 231 - 1
My Solution
Right off, if n is negative, we can return false. Then we keep dividing by 3 until the number is no longer divisible by 3 or it equals 1.
Time complexity of this algorithm would be O(log n) because we keep dividing by 3. Space complexity is O(1) because it only requires constant extra space.
class Solution {
public boolean isPowerOfThree(int n) {
if (n <= 0) {
return false;
}
while (n > 1) {
if (n % 3 != 0) {
return false;
}
n /= 3;
}
return true;
}
}