x_Square.cpp

class Solution {
public:
    int mySqrt(int x) {
        int l = 0;
        int r = x;
        int mid;
        int ans = -1;

        while (l<r){
            mid = l+(r-l)/2;
            if (mid*mid<=x){
                ans = mid;
                l = mid+1;
            }
            else{
                r = mid-1;
            }
        }
        return ans;
    }
};