Guide to Competitive Programming

A typical C++ code template for competitive programming looks like this:

#include <bits/stdc++.h>
using namespace std;
int main() {
// solution comes here

The #include a line at the beginning of the code is a feature of the g++ compiler that allows us to include the entire standard library. Thus, it is not needed to separately include libraries such as iostream, vector, and algorithm, but rather they are available automatically.

The using line declares that the classes and functions of the standard library can be used directly in the code.

Without the using line we would have to write, for example, std::cout, but now it suffices to write cout.
The code can be compiled using the following command:
g++ -std=c++11 -O2 -Wall test.cpp -o test
This command produces a binary file test from the source code test.cpp. The compiler follows the C++11 standard (-std=c++11), optimizes the code (-O2), and shows warnings about possible errors (-Wall).