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February Lunchtime 2017

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Hi everybody!

I’d like you to invite for February Lunchtime that will start at 19:35 IST of 25-th February 2017 and will last 3 hours. The contest starts 5 minutes later than usually to avoid a clash with a contest on another online platform (AtCoder Mujin Contest).

I am an author of problems and editorials, while niyaznigmatul is a tester. I want to thank dpraveen (who is a contest admin) and suraj_sharma for their technical help. Translators: xcwgf666 (Russian), huzecong (Mandarin) and VNOI team (Vietnamese). Language verification: arjunarul.

As usually, there is no registration required — anybody with a CodeChef handle can participate. Top school participants can win CodeChef laddus (details on the contest page).

You will be provided 4 problems with subtasks (IOI-style grading), all featuring bear Limak. Ties are broken by time of reaching your final score. I honestly think that all problems are interesting and valuable — some for beginners and some for experiences competitors (IMO one particular problem is so new and beautiful). Remember about subtasks if you can't solve a problem for the full score, and read the editorial after the contest.

I wish you great fun and no frustrating bugs. Hope to see a lot of you in the leaderboard!

PS. Starting with this Lunchtime, every regular contest (Challenge, Cook-off and Lunchtime) will have its announcement in the forum. Here you can give us your feedback about problems, express your feelings (brag about your victory for example) or just discuss the contest. There still exist editorial topics though, so it's better to ask a particular question about a problem there. We hope you will like this idea.

asked 24 Feb '17, 17:32

errichto's gravatar image

5★errichto ♦♦
980118
accept rate: 30%

edited 24 Feb '17, 19:48


So which problems did you like the most? Which the least?

link

answered 25 Feb '17, 23:28

errichto's gravatar image

5★errichto ♦♦
980118
accept rate: 30%

Bear and bribing Tree :) can we get the editorial for the problem.

(25 Feb '17, 23:35) adijimmy5★

The editorial was uploaded 15 minutes ago - https://discuss.codechef.com/questions/91951/bribetr-editorial

(25 Feb '17, 23:54) errichto ♦♦5★

Bear and House Queries

Such a nice problem on Binary search and observation :)

(26 Feb '17, 01:04) tihorsharma1233★

The problem I liked the most was QHOUSE and the least was OVERPNT. I don't think OVERPNT was a bad problem. Infact it was a good one but it was surely not meant for me.

(26 Feb '17, 11:09) mathecodician4★

can anyone write more detailed editorial for Bear and bribing tree problem from the February lunch time. I had looked at it's editorial and I found it very difficult to understand. Can anyone explain it with the proper DP approach including overlapping sub problems and brute force solution, how that problem fits in that problem, everything in very detailed way so that it could be even understood by beginners. The problem with the official editorial is that it directly talks about the dp solution and I am still not able to realize how it is a DP problem.

link

answered 26 Feb '17, 14:19

arpit728's gravatar image

1★arpit728
6831563
accept rate: 10%

Lunchtime is basically meant for school students but as codechef allows everyone to participate in this competition, how are school students gonna win exiting prizes through this?

I am too a beginner in programming, could solve one or two problems among the four, when will I be enable to win prizes through Lunchtime or even Cookoff?

link

answered 25 Feb '17, 14:51

bhushan_'s gravatar image

5★bhushan_
926
accept rate: 9%

3

Only school students are eligible for prizes so it doesn't matter that everybody is allowed to participate. It's up to you how much you learn and train. For sure participating in contests is one of things that will make you stronger and thus closer to winning prizes eventually.

(25 Feb '17, 15:59) errichto ♦♦5★

@errichto ♦♦ I agree to the fact that participating in contests is way much more important than just to think about winning prizes :P

(25 Feb '17, 19:13) bhushan_5★

Feedback? Interesting!

1 quick Q tho, in case someone finds discrepancy/doubt in a Q, will he now have to ask it here(cause its also 'feedback' in a way) or in the comments of the problem?

link

answered 24 Feb '17, 17:41

vijju123's gravatar image

4★vijju123 ♦♦
15.2k11859
accept rate: 18%

3

@vijju123: If the discrepancy/doubt in a question is during the live contest, you should ask that to the moderators by writing comments on the problem.

However, you can discuss that up after the end of contest here also.

(24 Feb '17, 17:44) dpraveen ♦♦4★
3

Questions related to the statement (e.g. understanding of some definition or not clear example test) should be posted in comments under a problem. The forum should be used before and after the contest, generally.

(24 Feb '17, 17:47) errichto ♦♦5★

Thanks for the clarification, both of you :)

(24 Feb '17, 18:31) vijju123 ♦♦4★

please post the editorial of BRIBETR...Thank you.

link

answered 25 Feb '17, 23:38

mach_hack123's gravatar image

5★mach_hack123
1
accept rate: 0%

The editorial was uploaded 15 minutes ago - https://discuss.codechef.com/questions/91951/bribetr-editorial

(25 Feb '17, 23:54) errichto ♦♦5★

Which one of the problem was the new and beautiful one? OVERPNT?

link

answered 26 Feb '17, 00:34

mathecodician's gravatar image

4★mathecodician
2.6k1930
accept rate: 7%

edited 26 Feb '17, 00:34

can anyone write more detailed editorial for Bear and bribing tree problem from the February lunch time. I had looked at it's editorial and I found it very difficult to understand. Can anyone explain it with the proper DP approach including overlapping sub problems and brute force solution, how that problem fits in that problem, everything in very detailed way so that it could be even understood by beginners. The problem with the official editorial is that it directly talks about the dp solution and I am still not able to realize how it is a DP problem.

(26 Feb '17, 14:19) arpit7281★

yes, OVERPNT was that one.

(26 Feb '17, 14:55) dpraveen ♦♦4★

Feedback
The problems were really delicious(as expected by codechef and good for an intermediate beginner like me. There is lot to learn from this contest, especially the problem with application of binary search. I am having fun by upsolving the problems. After contest I have seen Gennady's solution, he writes very clean and elegant code.

link

answered 26 Feb '17, 16:59

swamicoder's gravatar image

4★swamicoder
2347
accept rate: 10%

Editorial links need to be added to the practice problem pages.

link

answered 26 Feb '17, 17:14

pratik_gadhiya's gravatar image

4★pratik_gadhiya
228110
accept rate: 10%

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question asked: 24 Feb '17, 17:32

question was seen: 2,499 times

last updated: 26 Feb '17, 17:14