二分法实现开方运算

public int sqrt(int x) {
        int low = 0;
        int high = x;
        while (low <= high) {
            long mid = (low + high) / 2;//防止溢出
            if (mid * mid == x)
                return (int) mid;
            else if (mid * mid < x)
                low = (int) (mid + 1);
            else
                high = (int) (mid - 1);
        }
        return high;
    }
}