Story of a Robot | CodinGame Winners for 09/21/2013


The September CodinGame was our first themed CodinGame, with guest star Bender, the robot-with-all-the-vices-in-the-world. In the end, this was one of our favorite challenges.

For one, the exercises were truly complementary; for another, we loved having Bender as the star of the show; and finally, because we find more and more CodinGamers coming from all corners of the globe, and we love seeing participants from new countries.

Of the 3,445 entries, 1,124 held up to the end. And it should be said that the overall level of the entries was pretty great. With a 3rd exercise that some coders we know would call “Japanese Torture”, the challenge required you to juggle several skills.


1st exercise: Bender, the depressed robot: this exercise didn’t require a great deal of algorithmic complexity, but it did require you to produce a lot of code. The challenge was in accounting for a large number of rules, and, to avoid ending up with 500 lines of code, you had to develop a state machine. Another element: showing maximum rigor at each stage.

PS: We're very sorry about the problem which occurred with the map displayed in the example. Though the validators were OK, the map that we displayed was wrong. We corrected it quickly and hope you did not loose too much time because of that.

2nd exercise: Bender’s money machine: this problem was more algorithmically oriented. At first glance, it seemed to call for a quick, “brute force” solution, but that left the last few contestants to come up with special optimization techniques. This became a dynamic programming problem, which required, at each step, to be able to store Bender’s route through the chambers in memory. It was possible to get away with pretty compact code, if you didn’t miss the chance to optimize.

3rd exercise: Bender’s complexity: Here we had a problem that was clearly mathematical. Even if you detected the appropriate complexity with implementations that were not necessarily optimal, and you weren’t limited by runtime problems, you still had to figure out the trick to detecting the progression of the curve and to comparing it to the progression of all potential algorithmic complexities.

>>> You can attempt the exercises again via the training page.


Take a look at the rankings here, with links to the source codes of the participants:!ranking:15


This time, it was hard to get a perfect score in less than an hour’s struggle with this challenge. The first to finish was ACube, but … that cost him a fatal 2% and prevented him from taking first place on the podium.

The victor this time was kjus, who took first place in 01:50:12, and that too in C++!. Manger followed just behind him in second place at 01:52:22, the whole thing in C#. And finally, uuu vvv, our intergalactic hero, took 3rd position, in a total time of 02:01:25.


For this challenge, word got around and we had 1,000 more entrants than we did for the July challenge. Entrants come from more than 55 different countries.  In the top 10 countries represented: India, France, Morroco, Tunisia, USA, Brazil, Cameroon, Vietnam, Romania, and Algeria.


Come back on November 23!


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