Introduction

Welcome to the Competitive Programming Setup Guide, utilizing a proven and efficient setup for long-term success! Whether you're aiming to excel in contests like ICPC or enhance your coding abilities for technical interviews, this guide gets you started quickly and effectively.

By following this guide, you'll:

• Set up a contest-like development environment.
• Master a pro-like yet simple setup for coding challenges.
• Learn how to solve problems on platforms like Codeforces from start to finish.

Table of Contents

• Environment Setup
  • WSL Setup (Windows Users)
    • Optional: Rename Instance
  • Ubuntu Setup (Everyone)
• Solve a Problem on Codeforces
  • 1. Choose a Problem
  • 2. Solve the Problem
  • 3. Compile and Test Locally
  • 4. Submit Your Solution
• Commandline Usage
  • Compiling
  • Input and Output
• Explanations
  • program.cpp
  • debug.h
• Where to Go Next
  • Online Resources
  • Tools
• Contribute

Environment Setup

WSL Setup (Windows Users)

This is for Windows Users; Linux users can skip this.

Since platforms like Codeforces and local contests like ICPC run on Linux-based OS, we use WSL with Ubuntu to match that official environment (https://docs.icpc.global/worldfinals-programming-environment/). It's simpler than using Windows tools and doesn't affect speed.

1. Right-click the Start Menu -> PowerShell/Terminal (Admin).
2. Type wsl --install.
3. Restart your PC.
4. Launch Ubuntu from the Start Menu and set up your user.

Optional: Rename WSL Instance

Click to expand

If you already have WSL installed or plan to have multiple instances, organizing them helps.

1. Open a new PowerShell/Terminal (Admin).
2. Install an additional instance: wsl --install -d Ubuntu-24.04.
3. Create a folder for new WSL instances: mkdir C:\WSL.
4. Export the instance: wsl --export Ubuntu-24.04 C:\WSL\UbuntuBackup.tar.
5. Unregister the instance: wsl --unregister Ubuntu-24.04.
6. Register the instance with a custom name: wsl --import CompetitiveProgramming C:\WSL\CompetitiveProgramming C:\WSL\UbuntuBackup.tar.
7. Open Terminal and select your new Ubuntu instance CompetitiveProgramming from the + dropdown.

Ubuntu Setup (Everyone)

1. Update everything: sudo apt update && sudo apt upgrade -y.
2. Install development tools: sudo apt install -y build-essential git.
3. Install your preferred IDE or text editor (e.g., install Visual Studio Code on Windows: https://code.visualstudio.com/download, and add the extensions WSL and C/C++).
4. Clone this GitHub repo: git clone https://github.com/FreGeh/competitiveProgrammingSetup.git CompetitiveProgramming.
5. Navigate to the new folder: cd CompetitiveProgramming/.
6. Open the folder or program.cpp in your IDE/text editor (VSCode: code .).

Solve a Problem on Codeforces

1. Choose a Problem

1. Visit Codeforces (https://codeforces.com/) and log in or sign up.
2. For starter problems, go to Problemsets and sort by the number of people who have solved them. For example, Medium Number (https://codeforces.com/problemset/problem/1760/A).

2. Solve the Problem

1. Read the problem description carefully.
2. Paste the example input into input.txt and the example output into output.txt.
3. Think of a solution and write it in the void solve() function.

3. Compile and Test Locally

1. Open your Ubuntu Terminal cd ~/CompetitiveProgramming and compile your code: g++ -std=c++20 -O2 -Wall program.cpp -o program.
2. Test with example input: ./program < input.txt.
3. Compare output:
   • If correct, submit.
   • If incorrect, debug with the debug() function, place it anywhere you want to analyze the variable behaviour.

4. Submit Your Solution

1. Scroll down and select GNU G++20 under Submit?. Upload your c++ code, then click Submit.
2. Check your submissions page for the verdict. If a test fails, copy the test case to debug locally further.

Commandline Usage

Compiling

g++ -std=c++20 -O2 -Wall -DDEBUG program.cpp -o program

• g++: GNU Compiler Collection (GCC) C++ Compiler.
• -std=c++20: Specifies that the C++20 standard should be used.
• -O2: Enables level 2 optimizations during compilation, improving runtime performance.
• -Wall: Activates all basic warning messages.
• -DDEBUG: Includes our debug utilities if required.
• -o program: Specify the name of the output file.

Input and Output

• ./program < input.txt: Uses input.txt as input.
• ./program < input.txt > output.txt: Saves output to output.txt.

Explanations

program.cpp

Head

• #include <bits/stdc++.h>: Includes all standard library headers in one line. (Use individual headers to slightly reduce compilation time.)
• using namespace std;: Avoids the repetitive prefix std::.
• typedef long long ll;: Shortens long long to ll.
• #ifdef DEBUG Conditional compilation: If compiled with (-DDEBUG) includes custom debug utilities #include "debug.h". Otherwise #define debug(...) do { } while(0) to not interfere if accidentally still used in code.

Body

void solve() The main logic for each test case goes here. Inputs are read via cin and results are output via cout.

main() Function: Handles setup and test case execution:

• Optimizes I/O: ios::sync_with_stdio(false); speeds up input/output operations.
• Automatic flushing enabled cin.tie(nullptr); when not debugging: #ifndef DEBUG.
• Reads the number of test cases tests and calls solve() for each. (Tip: If the problem has no test cases, set int tests = 1 and comment out cin >> tests;)

debug.h

• #pragma once: Ensures the header file is included only once in the program to prevent redefinitions.
• dbg_out() (base case): Prints a newline when no arguments are passed, acting as the termination point for recursive calls.
• dbg_out(Head, Tail...): A templated function that recursively processes and outputs multiple arguments to cerr, separated by spaces.
• #define debug(...): A macro that:
  • Prints debug messages to cerr in red (\033[31m), including the file name (__FILE__) and line number (__LINE__) where the macro is called.
  • Formats the output by displaying the variable names (#__VA_ARGS__) followed by their values, leveraging the dbg_out function.
  • Resets text formatting with \033[0m.

This setup allows efficient debugging by integrating variable inspection directly into your code without impacting the production build.

Where to Go Next

Competitive Programming is a transformative journey that seems way too big and complicated at the beginning, but let's you gradually improve and understand more about many aspects of modern Computer Science. So don't give up easily, but keep going by solving a problem each day :)

Online Resources

• Codeforces (Top problem-solving platform): codeforces.com
• CP-Algorithms Wiki (Helpful articles and guides): cp-algorithms.com
• GeeksforGeeks CP Handbook (Step-by-step chapters): geeksforgeeks.org/competitive-programming-cp-handbook-with-complete-roadmap
• MIT OpenCourseWare (Free video lectures and resources):
  • Algorithms: ocw.mit.edu/courses/6-006-introduction-to-algorithms-spring-2020
  • Advanced Algorithms: ocw.mit.edu/courses/6-854j-advanced-algorithms-fall-2008
• Algorithms by Robert Sedgewick and Kevin Wayne (Highly-rated online book): algs4.cs.princeton.edu/home
• CP Ressources Wiki: github.com/lnishan/awesome-competitive-programming

Tools

• Tampermonkey Script (Highlights relevant math variables/notations so you can read problems easier): greasyfork.org(made by me)

Contribute

Thank you for the interest in this page :) I would appreciate any help to keep it up to date and fix any errors and add improvements if needed.

How

1. For new additions or specific modifications create Pull Requests
2. For general suggestions create an Issue
3. Or just message me directly per E-Mail ([email protected])

ToDos

• add more ressources, but keep it short
• better explanations that are precise and understandable even for beginners
• add screenshots/gifs where needed
• improve visual appeal
• youtube video going through everything
  • showing how to solve any problem with it