### mgch's blog

By mgch, 4 years ago,

Hello CodeForces Community!

We’re excited to announce the July Lunchtime 2018 sponsored by ShareChat. We hope to see you all join us in these 3 intense hours of coding challenges. Plus there are some exciting job and internship opportunities by ShareChat for participants of July Lunchtime. For more details please visit the contest page here: https://www.codechef.com/LTIME62

Joining me on the problem setting panel are:

• Problem Setter: Fekete (Ivan Fekete)
• Problem Tester: mgch (Misha Chorniy)
• Editorialist: likecs (Bhuvnesh Jain)
• Statement Verifier: Xellos (Jakub Safin)
• Russian Translator: Mediocrity (Fedor Korobeinikov)
• Mandarin Translator: huzecong (Hu Zecong)
• Vietnamese Translator: VNOI Team

### Contest Details:

Time: 28th July 2018 (1930 hrs — 2230 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone

Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.

Prizes: Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here: https://discuss.codechef.com/questions/51999/how-do-i-win-a-codechef-goodie. (For those who have not yet received their previous winning, please send an email to winners@codechef.com)

Good Luck! Hope to see you at the contest!

• +56

 » 4 years ago, # |   0 5 problems in both divisions.am I right?
•  » » 4 years ago, # ^ |   +11 Yes, you're right
•  » » » 4 years ago, # ^ |   0 ok, thanks.
 » 4 years ago, # |   +26 system stopped :(
•  » » 4 years ago, # ^ |   +46 CodeChef is celebrating "500 Internal Server Error" on account of 500th Codeforces Round :xD
•  » » » 4 years ago, # ^ |   +1 Lol xD The reason of such queue is using SPOJ's backend by CodeChef and it's not scalable at all :( Most probably, the contest will be extended by 45 minutes.
•  » » » » 4 years ago, # ^ |   0 loved prime divisors problem
•  » » » » 4 years ago, # ^ |   +1 But contest has ended already :(
•  » » » » 4 years ago, # ^ |   +9 the contest was reopened but I cannot submit because of stopped submissions message :(
•  » » » » » 4 years ago, # ^ |   0 me too..huh
•  » » » » » 4 years ago, # ^ |   0 Yes... Seems the contest will be unrated, sorry :( I don't know why it happened.
•  » » » » » » 4 years ago, # ^ |   0 no problem boss it happen's sometimes. tasks were good
•  » » » » » » 4 years ago, # ^ |   +11 what about laddus? :)
•  » » » » » » » 4 years ago, # ^ | ← Rev. 2 →   0 Laddus are not decided yet. You can ask PraveenDhinwa about them later.
•  » » » » » » » » 4 years ago, # ^ |   0 it will be rated or not mgch?
 » 4 years ago, # |   +8 Task were interesting, thanks !I think round should be unrated, conditions were same for everyone, but again it is not same situation if you have 2 hours or 3 hours.
 » 4 years ago, # |   0 how we will submit solution,if it has been locked ?
•  » » 4 years ago, # ^ |   0 UPD: it is open now
 » 4 years ago, # |   +6 I think "MEX and Ranges" problem is similar to this CF problem. I directly copied my online solution from that problem and submitted. Unfortunately timit limit is too strict, that is why 2 testcases in the last subtask do not pass. But I believe with some optimizations, I can get full score. My solution works in O(N5 / 3).
•  » » 4 years ago, # ^ |   +10 actually this complexity is intended to get TLE, the fact that MEXRNG doesn't ask for updates will allow O(q sqrt n) solution, but yes this problem is really similar if we were aware of it we wouldn't use the version without update.
•  » » 4 years ago, # ^ |   0 That CF Problem allows offline solution, in fact, it seems like only offline solution is possible. How did you turn your solution into an online solution?
•  » » » 4 years ago, # ^ |   0
 » 4 years ago, # | ← Rev. 3 →   +17 Editorial for the first five problems is available: Hope you all enjoyed the problemset. :)
•  » » 4 years ago, # ^ |   +1 Editorial link for PRMDIV is broken. 404 Not Found .
•  » » » 4 years ago, # ^ |   +5 Fixed.
 » 4 years ago, # |   +3 well something really interesting happened today and I am having a really tough time understanding why my two solutions one Accepted and another TLE one takes 0.8s while another gives TLE at 3.1s and both are 99.9% same and the only differnce is ACCEPTED ------------------ long nVal = 0; if (present[nKey]) { nVal = count[nKey]; if (sum[nKey] % sum[key] == 0) ans += nVal*value; } nKey += key; ------------------ TLE ------------------ long nVal = 0; if (present[nKey]) nVal = count[nKey]; if (sum[nKey]%sum[key] == 0 && present[nKey]) { ans += nVal*value; } nKey += key; ------------------ is % operation this much heavy
•  » » 4 years ago, # ^ |   0 Problem : prime divisors