Sqrt(x)

class Solution {
public:
    int mySqrt(int x) {
        if(x == 0 || x == 1)
            return x;
            
        int lt = 0, rt = x;
        while(lt <= rt)
        {
            int mid = (lt + rt) / 2;
            if(x / mid == mid)
                return mid;
            if(x / mid < mid)
                rt = mid - 1;
            else
                lt = mid + 1;
        }
        
        return rt;
    }
};