The 2019/20 SWERC (Southwestern European ICPC regional contest) takes place tomorrow January 26 at 9:15am CET in Paris. You should see the scoreboard here once the contest starts.
There will be an online mirror here and life streaming here
UPD: I have prepared a GYM based on the contest and it is available here. Many thanks to ko_osaga and the team Ruber Duck Forces (Infoshoc, nagibator and EvgeniyZh) for providing solutions to the problems.
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Oh, I made a blog without seeing this one. I'm removing mine then.
I'm in Paris as a commentator today. Tune in for ICPC Live broadcast:
Youtube — https://www.youtube.com/icpclive
Twitch — https://www.twitch.tv/icpclive
I've heard that Errichto will be one of the commentators :P
Where to submit solutions after the contest ??
In problem E, I still don't understand how to do the Gaussian Elimination in
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. Can anyone explain this in more detail?That's what I would do:
Assume
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(the board is taller than wider). The input consists of bitsUnable to parse markup [type=CF_MATHJAX]
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) putting constraints on the final values in each cell.Let
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be the boolean variable describing whether you tapped on the cell in $$$i$$$-th row andUnable to parse markup [type=CF_MATHJAX]
-th column (Unable to parse markup [type=CF_MATHJAX]
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). We can now describe allUnable to parse markup [type=CF_MATHJAX]
as a linear combination of allUnable to parse markup [type=CF_MATHJAX]
and a constant $$$1$$$. When describingUnable to parse markup [type=CF_MATHJAX]
, we want to ensure that the final valueUnable to parse markup [type=CF_MATHJAX]
is correct; that is,Unable to parse markup [type=CF_MATHJAX]
. This allows us to describe allUnable to parse markup [type=CF_MATHJAX]
's inUnable to parse markup [type=CF_MATHJAX]
orUnable to parse markup [type=CF_MATHJAX]
time.For instance,
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, and thenUnable to parse markup [type=CF_MATHJAX]
Now notice that we only need to ensure the correctness of the bits in the final row (all previous rows were taken care of when assigning $x_{\star, \star}$). This is equivalent to solving a system of
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linear equations (each describing a cell in the final row) withUnable to parse markup [type=CF_MATHJAX]
variables (each describing a cell in the first row), which takesUnable to parse markup [type=CF_MATHJAX]
orUnable to parse markup [type=CF_MATHJAX]
time. After solving the system, it's straightforward to restore the correct values of all remaining variablesUnable to parse markup [type=CF_MATHJAX]
,Unable to parse markup [type=CF_MATHJAX]
.Will you upload it to the gym?
I am working on it, but I need to solve all the problems first to have a model solution. I am not involved in the organization at all, but they have provided on their web page the tests so it should be feasible.
AC codes for ABCEFHK
Many thanks
404 not find，Can you post it again？
Auto comment: topic has been updated by mathusalen (previous revision, new revision, compare).
How to solve K?
Editorial if anyone is looking for it: https://swerc.eu/2019/theme/problems/swerc-analysis.pdf
Thank-you. I have added the link to the resources of the gym.