shubhamgoyal__'s blog

By shubhamgoyal__, history, 5 years ago, In English

Hello Codeforces Community!!!

I invite you all to take part in HackerEarth's January Easy contest.The contest will be held on 1st January,2018 at 22:00 IST.

Problems have been set by me(shubhamgoyal__) and tested by MiteshAgrawal.We are grateful to HackerEarth admin prat33k for his help.

You will be given 5 algorithmic problems to solve in 3 hours. Partial scoring will be used (you get points for passing each test case). Although the contest is targeted towards beginners, we hope even experienced problem-solvers find one or two problems to be interesting. The contest is rated and prizes will be awarded to the top 3 beginners(i.e. Programmers with a rating of 1600 or less before the challenge starts).

Good luck and have fun.

UPDATE1: Close to 3 hours left in the contest.

UPDATE2: Contest has started.

 
 
 
 
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5 years ago, # |
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Auto comment: topic has been updated by shubhamgoyal__ (previous revision, new revision, compare).

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

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

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

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5 years ago, # |
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Really excited for this one !

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January Easy' 18 Bro!

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

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5 years ago, # |
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hope some problems will also be "easy" for beginners !!!

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

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5 years ago, # |
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What was the expected solution for Shubham and Subarrays ?

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    5 years ago, # ^ |
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    Hashing

    Solution

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      5 years ago, # ^ |
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      Can you explain a bit more ? How are you making sure (x,y) and (y,x) are same ?

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        5 years ago, # ^ |
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        Suppose hash function for value x returns basex for some base.Then hash value for (x,y) would be basex + basey and hash value for (y,x) would be basey + basex.So you can see both arrays map to the same hash value.

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          5 years ago, # ^ |
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          Is there a particular reason you have chosen 127 and 129 as bases?

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          5 years ago, # ^ |
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          Also, why have we used two bases? Why not hashing using just one, and storing it?

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            5 years ago, # ^ |
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            You can choose any base of your choice as long as there are no collisions.The reason for choosing 2 bases is also to prevent collisions.

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              5 years ago, # ^ |
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              How do we know whether the collisions will happen or not?

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        5 years ago, # ^ |
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        I got 100 points even without using hash , tests are very weak. For the hash solution , just rolling hash this string (see code) for avoid mle =) if they are the same, they hash value will be the same.

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In Shubham and tree — 1

How can answer for distinct costs can be zero for any node???

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5 years ago, # |
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I have a question that how many people will get T-Shirt? Only 3 or 100 people. actually I am new on hackerearth and only did this contest and ranked 80. can I got T-Shirt?

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    5 years ago, # ^ |
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    Hi,

    We provide T-Shirts to the first 5 eligible participants. Better luck next time :)

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      5 years ago, # ^ |
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      So is it 5 or 3. be specific?

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      But there said beginner who have 1600 or less ratting who all are eligible for T-shirt then why only 3? Isn't a poor work ?

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I guess I overkilled C with persistent trie.

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    5 years ago, # ^ |
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    Can you explain how did you solve using persistent trie ?

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      5 years ago, # ^ |
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      Sure.

      For every index i, maintain a trie which has all the possible subarray sums in a[1..i]. Again iterate over i, and select j <= i. You have to find the value in the trie till j — 1 which gives maximum xor value with . Do it for all 1 < j <= i.

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How to do C??

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Really bad issue with test cases, hoping for rejudging. First time that I won a contest. : )

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    5 years ago, # ^ |
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    because of no one Pro coder didn't participate :p

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    5 years ago, # ^ |
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    We are looking into the matter.We will update everyone soon.

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    5 years ago, # ^ |
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    Hi,

    We have rejudged the required submissions. We apologise if you faced any issue. Congratulations for the first rank :)