69.Sqrt(x).cpp

class Solution {
public:
    int mySqrt(int x) {
        long long l = 0, r = x, ans = 0;
        while(l <= r){
            long long mid = l + (r - l)/2;
            
            if(mid * mid <= x){
                ans = mid;
                l = mid + 1;
            }
            else r = mid - 1;
        }
      
        return ans;
    }
};