parthkris13 / cc

Getting into Competitive Coding

Programming is all about writing code to solve problems or tasks. Competitive programming makes a sport out of this, where contestants compete (usually online) to solve a bunch of such problems in a limited amount of time.

What's in a problem?

Problems are primarily math, logic and/or algorithm based and typically look something like this. Such problems usually consist of a statement (that details the task), the input and output format, constraints on the input and some examples (will be further explained later on).

Try this problem. Read the statement carefully and try to understand what it is asking. Once you figure it out, all that's left is to code.

Here's what one of the many possible solutions looks like.

C++ code

#include <bits/stdc++.h>
using namespace std;

int main() {
    int n;
    cin >> n;
    while(n--) {
        string s;
        cin >> s;
        if(s.length() <= 10)
            cout << s << endl;
        else
            cout << s.front() << s.length()-2 << s.back() << endl; 
    }
    return 0;
}

Choosing a language

Most competitive programmers prefer C++, and for good reason. However, Java and Python are also fairly popular. Knowing a programming language is the only pre-requisite.

Note: The code snippets in this guide will be in C++ since it is arguably the best language for competitive programming and not because I do not know any other languages :/

Setting up an IDE

If you haven't already set up an IDE, you may find use for one of the following links.
Link to setting up Sublime
Link to VS extension (cph)

Competitive coding platforms

There are many platforms that host programming contests and allow you to practice solving problems, among other things. One such platform is Codeforces, which I primarily recommend and use.

Here is a detailed guide I've written about problem statements, how contests work and the rating system on Codeforces (and a few other platforms).

Get started

Head on over to problemset on Codeforces and sort by rating. Solve some easy problems till you get a feel for it.

What's next?

Once you familiarize yourself with these things, here are some things you could consider doing next:

• Take a look at time and space complexity, as will you soon realise that not all logically 'correct' solutions pass the given constraints.

• Learn C++ STL. STL, or Standard Template Library, is a huge library of useful functions. If you're not already familiar with it, this is a good place to start. Try out a few problems here.

• Develop your problem solving approach by tackling topics one at a time. Here's a collection of some common beginner topics and problems on the same.

• Turn to the codeforces problemset, and sort by difficulty and tags. Grind problems because there's nothing like practice, practice, practice.

• Participate in live contests or take virtual ones. Virtual contests are a way to participate in or experience old contests that have happened in the past.

The secret formula

In all seriousness though
Learn new topic > Practice problems > Improve speed > Learn new topic > Practice ... Rinse and repeat.

Extras

Track your progress
Codeforces Practice Tracker
Rating Predictor (Download the extension)