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The Matrix 2021

Start date: Jan. 30, 2021, 5 p.m. UTC
Find the side length of the biggest black square in a matrix. In each column, black cells start at the bottom of the matrix and count up.

To kick off 2021 we present The Matrix Challenge!

The first 3 developers to solve the challenge perfectly in the least amount of time will be added to the Codility Hall of Fame, winning a package of swag and bragging rights. We’ll also be selecting 3 gold certificate winners randomly to win a package of swag.

Once the Matrix Challenge has ended (in two weeks), you will still be able to take the challenge, and gain certificates, but will no longer be in the running for prizes.

About Codility:

We help engineering leaders hire great software developers into their teams by evaluating technical skills in an unbiased way. We’re committed to leveling the playing field by building a platform that provides equal opportunity to all developers worldwide.

Good luck solving this Challenge!

The challenge is now over, but you may still practice on this task. Below, you can also find a video with explanation of possible solutions for the task:


4439 started 985 silver awards 284 golden awards

Hall of fame:

Md Abedin
Time: 4 minutes
Peng Cao
Time: 6 minutes
Nafis Sadique
Time: 6 minutes