[leetcode] problem 367 – valid perfect square

public boolean (int num) {
    int start = 1;
    int end = num;

    while (start <= end) {
        int mid = start + (end - start) / 2;
        float divide = num / (float) mid;

        if (mid == divide)
            return true;
        else if (mid > divide)
            end = mid - 1;
        else
            start = mid + 1;
    }

    return false;
}