hmehta's blog

TCO21 Algorithm Round 2A
By hmehta, history, 4 years ago, In English

Hello Everyone!

The TCO21 Algorithm Round 2A and its Parallel Round is scheduled to be held on Saturday, May 22 at 12:00 UTC -4.

Both the matches will be **rated**.

Please note that you must register for this round in the Arena. Registration is now open for the round in the Arena or Applet and will close 5 minutes before the match begins, so make sure that you are all ready to go. Click here to what time it starts in your area.

Members eligible to compete in Round 2A include:
- Members who won an Automatic Berth* a.k.a Bye* for Round 1
- Advancers to Round 2 from Round 1A or Round 1B

Members eligible to compete in the Parallel Round include:
- Members who did not qualify for Round 2
- Members who didn't compete in Online Round 1
- Qualifiers for Round 4 or TCO21 Algorithm Finals from Online Stages 1,2 and 3

Don’t know how to compete in Topcoder Algorithm Competitions?

Check out this guide to successfully compete in an algorithm match.

You can compete using:

  • Topcoder Java Applet - You can refer to this guide here to set up the applet. (Note that those who have Java 8 installed on their machine will see a security issue — You will have to add Topcoder in security exceptions in Java Control Panel. Please refer to the details in the guide.)
  • Topcoder Web Arena(Beta) - Please watch this video for step by step guide

Best of luck to you in the Arena!

- The Topcoder Community team

  • Vote: I like it
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  • Vote: I do not like it

Comments Comments (24)
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4 years ago, # |
  Vote: I like it +8 Vote: I do not like it

Arena logged me off as soon as the round started and it's not letting me get back in. Am I the only one having the issue?

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    4 years ago, # ^ |
    ← Rev. 4   Vote: I like it 0 Vote: I do not like it

    Saw that no one mention it besides you: I luckily didn't have the problem during the contest, but I cannot enter right now (getting the auth0 screen repeatedly).

    edit: For what it's worth, logging with username & password instead of google oAuth, seem to fix this for me.

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4 years ago, # |
  Vote: I like it +26 Vote: I do not like it

Medium: https://www.acmicpc.net/problem/12823

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4 years ago, # |
  Vote: I like it +50 Vote: I do not like it

Brilliant readforces + speedforces on the 250.

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    4 years ago, # ^ |
      Vote: I like it +24 Vote: I do not like it

    It should be topreader and topspeeder then.

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4 years ago, # |
  Vote: I like it +2 Vote: I do not like it

Editorial draft

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4 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Why the limit on medium is $$$65\,000$$$, if the solution is $$$O(n + m)$$$? With current limits, the obvious $$$O(\frac{nm}{64})$$$ passes.

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    4 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    I think creating $$$n$$$ bitset of size $$$n$$$ would cause MLE. I actually challenged someone who wrote that successfully.

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      4 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Use bitsets of $$$2^{14}$$$ and split problem onto 4

      (I actually have TLE with splitting to 8)

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    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Otherwise we should return vector<long long> and it seems to be a problem somehow?

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    4 years ago, # ^ |
    ← Rev. 3   Vote: I like it +12 Vote: I do not like it

    vector of ints is the return type, $$$\frac{n * (n + 1)}{2}$$$ won't fit into it otherwise. Though I don't see the point of not just asking for sum as a long long, or asking for a vector of long longs.

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    4 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    The obvious one gets MLE: 65000^2/2 bits is more than 256 MB. However, it fails only barely, so I used a non-bitwise bruteforce for vertices above 61000.

    It could've been intentional to let various solutions pass, but I agree that $$$O(nm/64)$$$ is a very uninspiring solution in Anno Domini duo milia viginti unus. I wrote it because while thinking about faster nicer solutions, I thought that maybe I'm falling into a trap and should just solve it in the most straightforward way... seems like it was a good decision.

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4 years ago, # |
  Vote: I like it +120 Vote: I do not like it

statement of 250 was too long to read :(

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    4 years ago, # ^ |
      Vote: I like it +66 Vote: I do not like it

    It was more like an ETS English test rather than competitive programming.

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4 years ago, # |
  Vote: I like it +29 Vote: I do not like it

I really really hope you could move to cpp17 :)

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4 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I think the idea for Easy is interesting, interesting... but...

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4 years ago, # |
  Vote: I like it +26 Vote: I do not like it

I literally failed the 250 because i forgot about the dot at the end of "Wrong." and didn't advance for that. Biggest bottle job in the history of competitive programming lol.

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    4 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I fail 250 because instead of exampleGuess[0] + exampleGuess[1] I print AB and vice-versa, instead of exampleGuess[1] + exampleGuess[0] I print BA. And this passes the samples.

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4 years ago, # |
  Vote: I like it +25 Vote: I do not like it

misof thanks for contest.I think problem statement could have been made shorter.Avoiding terms like magic orb, a magic scroll and a magic twin blade and just simply using rock, paper and scissors would have shorten the statement.

Is there any idea behind using long problem statements in first problem ? I usually see this on topcoder.

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4 years ago, # |
  Vote: I like it +24 Vote: I do not like it

at least 80 percent of the guesses made by your program must be correct

As if the lengthy statement is not enough ¯\_(ツ)_/¯

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4 years ago, # |
← Rev. 3   Vote: I like it +7 Vote: I do not like it

Opened 250: HOLY CRAP just look at this gorgeous WALL OF TEXT on an one-hour contest! TL;DR: okay, we have rock-scissors-paper, we know nothing about what is where, and further it all would be shuffled in two different ways, uh-huh, and we just need to correctly guess which beats which... almost everytime, hm. Yes, I know precisely what to do with this problem (*Closes 250).

Opened 600: Yeah, this one definitely seems more doable. (*Spends 1h on Kosaraju, condensations and stuff only to conclude there are no viable ideas left.)

Reopened 250: Okay, we have about 10 more minutes to go, sure it is pretty enough time to submit some YOBA solutions on this one. (*Writes 10 lines, the solution passes samples... and systests) YOU GOTTA BE KIDDI

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