Valid Perfect Square

Given a positive integer num, write a function which returns True if num is a perfect square else False.

Note: Do not use any built-in library function such as sqrt.

Example 1:

Input: 16
Returns: True

Example 2:

Input: 14
Returns: False

public class Solution {
    public boolean isPerfectSquare(int num) {
        int low = 1, high = num;
        
        while (low <= high) {
            int mid = low + (high - low) / 2;
            
            if (mid == num / mid && num % mid == 0) return true;
            else if (mid > num / mid) high = mid - 1;
            else low = mid + 1;
        }
        return false;
    }
}