How to optimize IO in C++

Preface Link to the repository containing all examples Back when I was at my first class of Data Structures and Algorithms, I started to solve competitive programming questions in judges like CodeForces, I didn't know why my code was slower if my solution was efficient (at least in theory), my professor explain to the class the reason why our programs were slow, because of I/O is an expensive task for computers. To start working with the examples in this article just clone the repository and play with it as long the article explains how to run the code. git clone https://github.com/MiztonCodes/OptimizeIO.git Why std::cout and std::cin are slow? In C++ by default, both std::cin and std::cout streams are synchronized with standard C scanf and printf streams and at the same time every single call to std::cin flushes the std::cout buffer, because std::cin before reading input, wants to output any pending prompt to the user, which can cause performance issues because reading and writing are expensive tasks due to the need to make calls to the operating system, the solution is to disable all of this synchronizations and manually flushing the output buffer whenever it is needed. Note: For convenience in all examples I'll use #include<bits/stdc++.h> header to simplify the imports, this header includes everything we'll need and this header only works on GCC compiler. What is input and output? When you run your program, it is like an isolated box inside your computer, ready to do some work, the input process involves moving raw data from an external source like a keyboard, a file or even the network to your program (reading) , the output process involves moving data from your program to an external destination like a monitor, the console, a file, the network or even an external device (writing) , for both processes your program does not read or write directly to the input and output sources, because each source has its own way to transfer data, C++ provides a uniform interfac