Life In 19x19

Sorry for replying rather late.

I have received a few emails regarding this problem, and this issue was raised also on github. Even though the issue might be caused by the line mentioned above, I do not really understand that (and also, as was mentioned, it seems to be a Windows specific problem ...

Today Windows Defender detected a trojan virus (Win32/Vagger!rfn) in the kombilo.exe

True threat or false positive?

Thanks for the notice.

I am very confident that this is a false positive, as far as the installer is concerned: I checked that the exe files which can be downloaded from u-go.net ...

Thanks, Solomon, for setting up the contest! Problem C in particular was quite instructive for me, so I enjoyed it.

Best, Ulrich

Congratulations to Ulrich for not only getting all 6, but for getting 5/6 in 1 try! I would be even more impressed if he passed all the test cases with Python :).

Thanks, Solomon, and thanks for setting up the contest! Yes, I did all of it in Python - the problems this time had a sufficiently ...

Thanks, Solomon, for taking up the contests again. I agree the week-long format is a good idea.

So now I'm curious how Ulrich solved problem D...

The basic idea was the following: Assume for simplicity that all numbers in the given sequence are different. Then given a query, i.e., an interval ...

Thanks, Solomon, for setting up the contest!

As to my solutions, I do not have much to add to what Bernd said - for A, B, C, and F, I did roughly the same as he described. I did not spend much time on D, it also looked like a graph theory problem to me, with the edges encoding that two entries are ...

A. Taking a difference in the final step, it is enough to compute the number of zeros needed to write down all numbers from 0 to n. To do this, I computed how often the i-th digit is a 0, for all i. This is quite easy: Say n = 12345, then for the 5th digit we get 1235, for the 4th digit we get ...

Thanks, Solomon, for setting up the contest! Here are some thoughts on my solutions:

A. Taking a difference in the final step, it is enough to compute the number of zeros needed to write down all numbers from 0 to n. To do this, I computed how often the i-th digit is a 0, for all i. This is quite ...

(Would you mind posting your solution, Solomon?
from sys import ...

Thanks! That's interesting, and I can see some points where this is faster than my solution ... but I guess I would have to create a large test case in order to see which of the differences really matters. (E.g., it is not ...

Thanks, Solomon, for setting up the contest!

This time, I found A, B, C pretty much straightforward. With D I had some problems to meet the time restrictions. (Would you mind posting your solution, Solomon? Since it is more than twice as fast as mine it would be interesting to compare. Form ...

Thanks, Solomon, for setting up the contest!

Some thoughts about the problems:

Problem A: Viewing the people as vertices of a graph, with an edge connecting those whose paths cross, the problem is to find the maximal length of a clique. My first tries did that without taking the special form of ...

Still puzzled how to get near the top in Power Strings.

I would guess that checking for prime divisors of the string length, and continuing with the initial piece of the string in the case of a hit, should be pretty fast. To save time, one should compute the list of primes only as far as required ...

Thanks, Solomon, for setting up another contest.

I liked the problems since for all of them there were enough sucessful submissions, also in Python, to prove that hitting the time limit means that the choice of algorithm is not ideal. (Although maybe true, this was not as obvious for the second ...

jeromie wrote:I seem to be having an odd problem parsing the file in problem F.

I had a similar problem until I noticed that the description says "The input for each room consists of one or more lines containing:".

Best regards,

Ulrich

For the curious, I put my solutions/attempts on github: https://github.com/ugoertz/l19contest. Comments welcome!

I was thinking of doing something like this after the first round, but decided against it - having the solutions googleable kind of breaks the concept of contest web sites.

I was ...