Kattis Algorithmic Athletics 2023

alt text On the Saturday of the May bank holiday weekend, four teams of courageous coders came together to compete in the Kattis Algorithmic Athletics here in the School of Computer Science at the University of Hull.

They were glorious, and this is how it all went down.

There were 7 puzzles to solve, and just 3 hours to do it in. It didn’t take long for the first puzzle to fall, just 11 minutes in to the contest. Team “TBA” dropped it in, all net, in one attempt. The puzzle was Minimal Fibonacci Sums where you had to find the shortest sequence of Fibonacci numbers that would add together to equal the target number.

12 minutes later Closing the Loop was solved by the team called “Mandela”. For this puzzle you were given a bag of pieces of rope that you had to tie together to make the longest loop. The catch is that each section of rope in the loop had to be in alternating red and blue pieces.

Just one minute later, and team “TBA” are back again, having completed Stacking Cups. In this puzzle there is a robot that is stacking different coloured cups, biggest at the bottom, smallest at the top. Unfortunately it sometimes measures radius and sometimes measures diameter.

The next puzzle to be solved takes a bit longer, and at the 41 minute mark team “Idk” solve the Fibonacci puzzle and team “Flight Mode” both conquer the confused cup stacking robot.

Team “Mandela” are next up with a neat stack of cups at the 48 minute mark.

At 55 minutes “TBA” finally crack Closest Sums on their 4th attempt. Until this point, all the puzzles have been solved on the first submission, and the 3 failed attempts may cost them dearly. The winners will be the team with the most puzzles solved, but ties are broken by time taken, and each failed attempt is penalised by 20 minutes.

At 2 minutes past the first hour, “Idk” stacks the cups.

“Mandela” solves the Fibonacci puzzle in the 74th minute moving them to the top of the leaderboard. At this stage, “TBA” and “Mandela” have both solved 3 puzzles each, but although “TBA” has been quickest each time, their 1 hour penalty has held them to second place.

But it didn’t hold them there very long as 15 minutes later, just before the half way point, “TBA” make a lovely loop of blue and red rope and use it to climb back to the top of the tree.

“Flight Mode” also achieve this 8 minutes later.

It seems that the Closest Sums puzzle is a bit tricky as it takes Mandela 3 attempts to finally bring it home at 114 minutes.

“Flight Mode” solve their 3rd and final puzzle just before the 2 hour mark. It was the Fibonacci one.

133 minutes in to the contest, and team “Idk” Close the Loop. This is their final solved puzzle, though they do make a failed attempt at the Closest Sums puzzle.

We are now in to the end game, and it is a two horse race to the finish between “TBA” and “Mandela”. With another costly 3rd attempt “TBA” manages to solve Smart Phone. For this puzzle you need to figure out which of the predictive phone text suggestions will require the fewest key presses to achieve the target word. There is only 25 minutes remaining in the contest.

“Mandela” solves the same puzzle 6 minutes later, but with one fewer attempts. Will that be enough?

No, but it was a great effort. In the end “TBA” had 100 minutes of penalty time, and “Mandela” only had one hour, but in the end “TBA”’s move fast and break things approach paid off. With 5 solved puzzles each, “TBA” won on speed.

The contest Scoreboard reveals the final standings to be “TBA” top, closely followed by “Mandela”, both with 5 solved puzzles. The second grouping has “Idk” just ahead of “Flight Mode”, both with 3 solved puzzles.

That leaves two puzzles that nobody solved. An Industrial Spy and Lawn Mower.

For the spy puzzle, you have to count how many unique prime numbers can be created by reordering a set of given digits. The lawn mower puzzle required you to monitor the efforts of the new grounds keeper to ensure that the pitch was appropriately trimmed.

Here is a complete list of the puzzles.

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If that all sounds pretty fun to you, then you can start practicing for the next one! Kattis is a nice platform that hosts literally thousands of these sorts of problems spanning a wide range of difficulty. Another nice aspect is that the automatic judge accepts solutions in a collection of different programming languages. So it is also a neat way to explore some of the differences in the languages by solving the same puzzle, but changing up the language.

In October there is also the UK and Ireland Programming Competition where university teams from all over the UK and Ireland will be competing.

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