alooochaat1998's blog

By alooochaat1998, history, 8 days ago, In English,

Hello, Codeforces!

I would like to invite you all to Alkhwarizm 2018, the flagship coding event of Aparoksha — The Annual tech fest of IIIT-Allahabad.

It will contain 10 tasks of varying difficulty and you will get 5 hours of time to fight this fierce battle of Codditch(another version of Quidditch).

The contest will be an External rated contest. We are happy to announce that Alkhwarizm 2017 was the first External rated contest in the history of Codechef and this year Alkhwarizm 2018 is the first External rated contest for both Divisions after the New Rating Division system on Codechef.

The problem setters and testers are me(alooochaat1998), blake_786 and priyanshupkm. Buckle up for an adventure ride through the wizarding world of Harry Potter once again. Each problem you solve will score a goal. Score all goals in this fierce battle of Codditch and we'll make sure that you get the lion's share in Monex Melicis (the money potion, another version of Felix Felicis).

The contest starts at 9:00PM (IST) on 16th March,2018. Check your timezone here.


  • The best wizard/witch will get a lion's share of 10K INR.

  • The 2nd best wizard/witch will get a panther's share of 6K INR.

  • The 3rd best wizard/witch will get a wolf's share of 4K INR.

  • Top 5 global winners and top 5 Indian winners will get 300 laddus each straight from the kitchen of Honeydukes.

Register right now at the link to be eligible for getting Monex Melicis. The contest is open for all but prize money is only for Top 3 college students from the global leader board.

Past Alkwarizm links : ALKH2017, ALKH2016, ALKH2013, ALKH2012.

Good luck everyone! Hope to see all wizards and witches on the leaderboard.

Reminder : Contest starts in 1 hour.

Update : It was great seeing so many submissions. Thank you for participating. Short Hints will be provided within 2 days since we are quite busy in tech-fest events. Also, detailed editorial will be announced within a week. Congratulations to all the winners. Thank you all for participating.

Update 2 : Sorry for removing the blog suddenly. I had forgotten to repost after saving the draft. Rest of the short hints will be updated within tomorrow.

Update 3 : All the short hints are given. Editorial will be posted within a week.

Short Hints:

  • Vote: I like it  
  • +69
  • Vote: I do not like it  

8 days ago, # |
  Vote: I like it 0 Vote: I do not like it

Auto comment: topic has been updated by alooochaat1998 (previous revision, new revision, compare).

5 days ago, # |
  Vote: I like it -50 Vote: I do not like it

Note: you can participate in Alkhwarizm contest only if you have Alzheimer.

4 days ago, # |
Rev. 2   Vote: I like it +11 Vote: I do not like it

Did the intended solution of HARRYHBP involve Centroid Decomposition + Implicit 2D segment tree?

I have a solution using these two DS. Complexity — O(N*(LogN)^3). But I thought it was an overkill. Also, TL was too strict for this complexity.

  • »
    4 days ago, # ^ |
    Rev. 2   Vote: I like it +10 Vote: I do not like it

    The intended solution was using centroid decomposition and fenwick tree with a complexity of O(n * logn * logn).

    We will be posting detailed solutions soon.

    EDIT : Hint for the problem is posted.