20220604 Mathematics: square root of X

        Title Description ： Give you a nonnegative integer  x , Calculate and return  x  Of   Arithmetical square root  . Because the return type is an integer , Results are retained only   Integral part  , The decimal part will be   Give up .

        coded ：

    public int mySqrt(int x) {
        int left = 0, right = x;
        while (left <= right) {
            int mid = (left + right) / 2;
            long pow = (long) mid * mid;
            if (pow > x) {
                right = mid - 1;
            } else if (pow < x) {
                left = mid + 1;
            } else {
                return mid;
            }
        }
        return right;
    }