Overview

What are the Informatics Olympiads?

Informatics olympiads are broadly a coding-equivalent of the math olympiads, and they lead upto the International Olympiad in Informatics (IOI).

These competitions give you problem statements and require you to code up solutions to them. This code is then tested using given input data, where your code's outputs are compared to the correct answers. Solving problems in these olympiads have two main steps:

Coming up with the algorithm - this is the more "math part" of the problem, and you need to figure out what set of steps you want to code up so as to solve the problem. In practice, there is usually an easy algorithm in the form of a bruteforce. However, the challenge is that these competitions set a limit on how much time your computer should take in order to solve the problem, and so these bruteforce methods are not usually efficient enough.
Implementing your algorithm - this requires you to code up the algorithm you came up with in a programming language such as C++, Python or Java.

How is this different from the coding at school?

The big difference is part 1. In practice, the coding we do at school usually tests knowledge of the right syntax - you should know how to take a substring of a string and print that. We may need some of that knowledge here too, but the main question here is "How do I come up with an algorithm that is efficient enough to run correctly?"

This step is what makes the contests fun as well, as they challenge you to think in a way similar to that in math olympiads, and test your creative as well as logicial skills.

Cool! Where do I start?

Here!