Hello Codeforces community !
I am glad to announce the first HackerRank HourRank round! The contest will be held on 15th October 2015 at 15:00 UTC. You can sign up for the contest here. Top 10 winners on the leaderboard will receive a HackerRank T-Shirt.
Problems have been set by Shafaet Ashraf (Shafaet) and Aleksa Plavsic (allllekssssa). Competitors will have 1 hour for solving 4 problems with variable scoring distribution. Contest are rated for all HackerRank users.
I want to thank whole HackerRank team for support and opportunity to organize the new format of competition. Especially I want to thank Shafaet, he is really great guy and his help and contributon in contest preparation are incredible. Also I want to thank wanbo and svanidz1 for testing tasks. I hope that this will become a traditional competition and we'll hang out in one of the following HackerRank contest :)
We are waiting your comments and suggestion about contest :)
Good luck and see you on Thursday !
UPD1: Score distribution : 30-40-60-80
The second and third problems have binary score.
UPD2: Contest starts in 15 minutes. Are you ready to become first HourRank winner ?
UPD3: Contest is finished. Editorial is published. Congratulation to winners :
2.Kostroma
3.anta
4.Lewin
Thank you for participation. I hope you enjoeyed in problems. I wish to hear more comments about task and contest. I will try to correct something in future if it is wrong. Thank you again and see you on next HourRank contest :)
Auto comment: topic has been updated by allllekssssa (previous revision, new revision, compare).
Auto comment: topic has been updated by allllekssssa (previous revision, new revision, compare).
Auto comment: topic has been updated by allllekssssa (previous revision, new revision, compare).
What about the level of the problems? For whom, you suppose, will they be interesting?
The tasks won't be very hard. I expect several top scores. At first I wanted a little harder contest, but HackerRank testers think that current tasks are better for the first round.
I give my best to invent new and interesting tasks :)
I am planning to do this contest. This will be my first contest in HackerRank. Very excited :D
Sorry for the stupid question but can somebody tell me what "binary score" mean?
Yes, 'binary score' means that your solution must pass all testcases for non-zero points.
Why nothing is written about prizes on Contest page?
Now everything is ok, you can check Contest page again :)
Top 10 users will get hackerrank t-shirt.
Warmup before #326 :)
The third problem was quite interesting, thank you!
How did you solve that one?
And what is asymthotic of my solution?
It's not greater than O(n * log^2 MAX)
Thanks for nice words :) You made this contest better and I hope you enjoyed in solving problems.
Second problem is awesome :)
Thank you. I tried to invent interesting and easy problems for implementation. Only I think that I made mistake with the easiest problem — for many logged it was very hard :)
Yes now after seeing the editorial it seems a very nice solution , i could not think of it during contest.
Awesome problems! At least the first 3, I didn't have time to read the 4-th but B and C are really really good, unfortunately I didn't have enough time to code B after I came up with the idea, it' pretty nice! :)
Auto comment: topic has been updated by allllekssssa (previous revision, new revision, compare).
I got trolled with Problem B. Thought knapsack, gaussian, trie and what not! Then I thought that it's suppose to be "Easy" category, so I should think simple. The category saved me :D
How did you solved this one?
Answer is either 0 or 2^(n-1)-1 :D
Answer is 0 when xor of all the elements of the array is 1 and otherwise, it is 2^(n-1)-1, if I am right. But how does this formula come from, can you give a little insight ?
Okay, we need to divide an array into two parts with equal xor. We know that A xor A = 0, so XOR of whole array must be 0 as well.
Okay, now we know that answer is 0 if array's XOR is not zero. Otherwise, let's choose any subset and call it L. And call other half as R. Then L xor R = 0 and R = 0 xor L = L. Finally we've got L = R and that's why we can divide an array in any way. So answer is 2^(n-1)-1.
Got it! Thanks.
allllekssssa sir ; All problems were very interesting...But,could not notice how fast the contest ended... :/
Contest are rated for all HackerRank usersAre you sure? Still no rating updates.Contest is rated, for sure. I don't work for HackerRank, so I can not tell you when rating will be updated.
The next HourRank round will be organized for 15 days and it will be prepared by svanidz1 ! I am really happy that they are support my idea and we have one new interesting contests in coder calendar :)
Thanks for the great contest! HourRank 3 is on Dec 2, 2 am — 3 am GMT/BST. Can't wait to participate in it!