When you use C++ and the input is really big you can't just use cin and cout. You need to speed up it with
Someone argues that the second line is unnecessary but it's not true. if the input and output alternate then adding the second line makes I/O more than twice faster. But then... Someone argues that we also need to use
I personally never use this and I don't know any case where it can help. So my question for today is the following: "Is there any case where we actually need
cout.tie? Or is it completely useless?"