Leetcode 367. Valid Perfect Square

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