Utkarsh.25dec's blog

Invitation to CodeChef Starters 69 — 14th December

By Utkarsh.25dec, 17 months ago, In English

We invite you to participate in CodeChef’s Starters 69, this Wednesday, 14th December, rated till 6-stars Coders (ie. for users with rating < 2500).

Time: 8 PM — 11:00 PM IST

Joining us on the problem setting panel are:

Written editorials will be available for all on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to Pro users.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

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Comments Comments (8)
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17 months ago, # |
  Vote: I like it +15 Vote: I do not like it

Starters 69- NICE

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17 months ago, # |
  Vote: I like it +17 Vote: I do not like it

This isn't usually a problem in Codechef, and I might be wrong here but PASSTHRU time limit for Java seems really tight. Too bad my C++ is rusty, I could not convert it within the contest.
TLE in Java. This was the closest I came to AC.
AC in CPP.

As for the problems, they seemed harder than usual (maybe it's just me losing touch).

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    17 months ago, # ^ |
      Vote: I like it +24 Vote: I do not like it

    The intended solution doesn't use small to large merging at all, but unfortunately we weren't able to stop it from passing in C++ (especially if some optimizations were used such as pragmas and/or fast hashmaps) so we decided to increase the TL a bit right before the contest; it's unfortunate that it didn't pass in Java (admittedly I don't know Java well enough to have tested that anyway). My C++ code runs in 0.7s so 2.5 seemed like a reasonable limit.

    However, I will add that the intended solution is $$$\mathcal{O}(N)$$$ after building the virtual tree so I hope that's fast enough in Java, check out the editorial if you're interested.

    Regarding difficulty: we expected way more solves on SORTPERM and ADJPAIRSWAP, but I'm guessing lots of participants got stuck on casework on them (or in DIVBYTHREE). ADJPAIRSWAP in particular has a rather clean solution with almost no casework, and SORTPERM is quite simple to implement after a couple of observations too.

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17 months ago, # |
  Vote: I like it +2 Vote: I do not like it

I used small-to-large merging, but my implementation kept giving TLE, please can anyone help ?

My last submission

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    17 months ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    Using unordered map might be the reason for tle. You can look at my submission using simple arrays and vectors. Submission

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17 months ago, # |
  Vote: I like it +4 Vote: I do not like it

Please make the announcement 1 day before the contest date on CF if possible from next time. :(

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17 months ago, # |
  Vote: I like it +3 Vote: I do not like it

My rank was 18 in this contest.

But my rating increased just by +32. I was expecting to become 6 star this time :(

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    17 months ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Check the rating increase of rank 1 in div2.

    He got +3.

    You have to get rank 1 20 times to get +60

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