Category Archives: Hacker Rank

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Lambda Calculi - March 2016 on HackerRank

Hello everyone,

I'd like to invite all of you to the Lambda Calculi - March 2016 contest hosted by HackerRank. The contest is a functional programming competition. It starts Mar 25 2016, 06:30 am CET and lasts for 3 days. The purpose of the contest is to test your functional programming skills starting from some basic concepts to harder algorithmic problems. 

The top 10 participants will be awarded with HackerRank T-shirts.

I'm the author of two harder problems in the contest, so I want to give you some clues about them. The first problem is purely about implementing a data structure (an extension a very well-known one), while the second one is going to test your ability to present some standard concepts used in imperative programming in a functional programming domain.

See you on leaderboard!

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HackerRank Regular Expresso Contest

Tomorrow a new type of contest will be hosted on HackerRank. It's going to be all about regular expressions - a concept that all software engineers should be aware of.

Register for the contest

The contest duration is set to 24 hours and top 10 participants will be awarded with HackerRank T-Shirts. I created two problems there and I'm going to take care of user questions during the contest. As a hint, I can tell you that most problems are not hard if you are familiar with regular expressions already, so speed will be a big factor here.

Have fun with it and see you on leaderboard!

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Indeed Prime Codesprint by HackerRank

Yesterday, I took part in Indeed Prime Codesprint hosted by HackerRank.

The contest duration was 24 hours, but I started solving problems when 8 hours were remaining. There were just 5 problems to solve and nice prizes for top 3 competitors as well as T-shirts for top 100.

I finished 72nd out of over 1400 total contestants. It was quite funny, because I struggled a lot with the 4th problem and when I got it finally accepted, there was very little time to write any solution to the hardest problem. Then I realized, that without solving it I would finished out of top 100, so I decided to write a dynamic programming solution, without any optimizations, and definitely too slow to pass all test cases. However, it was enough to pass over 1/3 of them, which gave me the final position and hopefully at least a T-shirt.

I want to mention that two hardest problems are worth to solve, because they require concepts and ideas every competitor basically must know, so if you want to practice or even learn something new, try them definitely.


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Zenefits CodeSprint on HackerRank

I haven't taken part in a 24 hour contest for a long time and when I got a notification that Zenefits is about to host a CodeSprint on HackerRank, I decided to take sign up.

The bad news that it started at 1 AM in my timezone, so not perfect if you want to sleep at night :) However, there were amazing prices to win, including cash, 10 trips to Zenefits HQ in US, and of course T-shirts. Prices attracted people as always, and the competition was quite strong.

There were 14 problems in the contest. I solved a few simpler in the first 2 hours, then went sleep and solved as many remaining ones as I could in the last 4 hours of the contest. This game me 89th place out of above 1000 competitors, at least qualifying me for a T-shirt. Probably, I should've slept about 6 hours rather than 12 that night :P this would give me required time to solve more problems and probably a place in the top 30.

I really like 24-48 hours contest format and I'm going to participate in more such competitions. It seems that HackerRank hosts a lot of such code sprints.

Last but not least, the problem set was really amazing. Setters did a great job, I encourage all of you to take a look at all the problems. There is even an optimization geometry problem with an intended linear programming solution, which I didn't figure out during the contest, because I totally forgot about this technique :P You can access all the problems here