[Math]Sqrt(x)

class Solution {
public:
    int mySqrt(int x) {
        if(x<0){
            return INT_MIN;
        }
        if(x==0){
            return 0;
        }
        long long int low = 1;
        long long int high= (long long int)x+1;
        while(low<high){
            long long int  mid = low + (high-low)/2;
            if(mid > x/mid){
                high = mid;
            }else if(mid == x/mid){
                return mid;
            }else{
                low = mid+1;
            }
        }
        return low-1;
    }
};