69. Sqrt(x) (Divide-and-Conquer)

class Solution {
public:
    int sqrt(int x) {

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