We invite you to participate in CodeChef’s Starters 89, this Wednesday, 10th May, rated till $$$5$$$-stars coders (i.e. for users with rating $$$< 2200$$$).

Time: 8:00 PM — 10:00 PM IST

Note that the duration is $$$2$$$ hours. Read about the recent CodeChef changes here.

Joining us on the problem-setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh
• Setters: Aniruddh Chimpanzee Patil, Subhash isheoran Sheoran, Manan mexomerf Grover, Dilshodbek DilshodbekX Khujaev, Wuhudsm wuhudsm, Jeevan JeevanJyot Jyot Singh, Hriday the_hyp0cr1t3, Rajat rajat397 Srivastava
• Tester: Nishank IceKnight1093 Suresh
• Statement Verifier: Jeevan JeevanJyot Jyot Singh
• Text Editorialist: Nishank IceKnight1093 Suresh
• Community Testers: Satyam satyam343 Kumar Roy, Varun Crime_and_Punishment Vaddiraju
• Video Editorialists: Sundar K Letscode_sundar, Madhav jhamadhav Jha, Suraj jhasuraj01 Jha, Jwala jwalapc, Adhish ak2006 Kancharla

Written editorials will be available for all on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to Pro users.

We’re hiring! If you’d like to work at CodeChef as a Learning Content Creator, click here.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 77, this Wednesday, 15th February, rated till 5-stars Coders (ie. for users with rating $$$< 2200$$$).

Time: 8 PM — 11:00 PM IST

Joining us on the problem-setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta
• Setters: Kanhaiya notsoloud1 Mohan, Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta, Yash PoPularPlusPlus Thakker, Laxman saini.laxman2002 Singh Saini
• Testers: Nishank IceKnight1093 Suresh, Jatin rivalq Garg
• Statement Verifier: Kanhaiya notsoloud1 Mohan
• Video Editorialists: Sundar K Letscode_sundar, Madhav jhamadhav Jha, Suraj jhasuraj01 Jha, Jwala jwalapc, Rohit ezo_tihor Oze, Adhish ak2006 Kancharla
• Text Editorialists: Nishank IceKnight1093 Suresh

Written editorials will be available for all on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to Pro users.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 74, this Wednesday, 18th January, rated till 6-stars Coders (ie. for users with rating $$$< 2500$$$).

Time: 8 PM — 11:00 PM IST

Joining us on the problem setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta
• Setters: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta, Kanhaiya notsoloud1 Mohan, Akib Finral_eCia Tonnoy, Ayush Ayu_19 Kumar, Dilshodbek DilshodbekX Khujaev, Chahat agrawal117 Agrawal, Pratik i.am.pratik Kumar, Chaithanya Dragonado Shyam D
• Testers: Nishant nishant403 Shah, Satyam satyam343
• Statement Verifier: Kanhaiya notsoloud1 Mohan
• Video Editorialists: Garvit garvitvirmani0 Virmani, Madhav jhamadhav Jha, Suraj jhasuraj01 Jha, Jwala jwalapc, Adhish ak2006 Kancharla
• Text Editorialists: Nishank IceKnight1093 Suresh

Written editorials will be available for all on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to Pro users.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 73, this Wednesday, 11th January, rated till 6-stars (i.e. for users with rating $$$< 2500$$$)

Time: 8 PM — 11:00 PM IST

Joining us on the problem-setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh, Lavish lavish315 Gupta
• Setters: Jeevan JeevanJyot Jyot Singh, Chaithanya Dragonado Shyam D, Stuart cstuart Lim, Zobayer Zobayer_Abedin Abedin, Harasees harasees_singh Singh, Dilshodbek DilshodbekX Khujaev
• Testers: Manan mexomerf Grover, Jatin rivalq Garg
• Statement Verifier: Jeevan JeevanJyot Jyot Singh
• Video Editorialists: Garvit garvitvirmani0 Virmani, Madhav jhamadhav Jha, Suraj jhasuraj01 Jha, Jwala jwalapc
• Text Editorialists: Nishank IceKnight1093 Suresh

Written editorials will be available for all on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to pro users.

Also, if you have some original and engaging problem ideas and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 61, this Wednesday, 19th October, rated for Div 2, 3 & 4 Coders.

Time: 8 PM — 11:00 PM IST

Joining us on the problem-setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta
• Setters: Jeevan JeevanJyot Jyot Singh
• Testers: Tejas tejas10p Pandey, Hriday the_hyp0cr1t3 G
• Statement Verifier: Hriday the_hyp0cr1t3 G
• Editorialists: Nishank IceKnight1093 Suresh

Additional Note about the Contest:

• All the problems in the contest were authored by me (JeevanJyot). I hope you like the contest :)

Written editorials will be available for all users on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day once the contest ends, after which they will be available to pro users.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 60, this Wednesday, 12th October, rated for Div 2, 3 & 4 Coders.

Time: 8 PM — 11:00 PM IST

Joining us on the problem setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta
• Setters: Jinlong wuhudsm Han, Utkarsh Utkarsh.25dec Gupta, Jeevan JeevanJyot Jyot Singh, Abhinav abhi_inav Gupta
• Testers: Tejas tejas10p Pandey
• Statement Verifier: Kanhaiya notsoloud1 Mohan
• Editorialists: Nishank IceKnight1093 Suresh

Written editorials will be available for all users on discuss.codechef.com. Pro users can find the editorials directly on the problem pages after the contest.

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to pro users.

If you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 55, this Wednesday, 7th September, rated for Div 2, 3 & 4 Coders.

Time: 8 PM — 11:00 PM IST

Joining us on the problem setting panel are:

• Contest Admins: Jeevan Jyot JeevanJyot Singh, Tejas tejas10p Pandey,

• Setters: Jeevan Jyot JeevanJyot Singh, Danny dannyboy20031204 Boy, Aaryan fishy15 Prakash, Saarang saarang Srinivasan

• Testers: Utkarsh Utkarsh.25dec Gupta, Hriday the_hyp0cr1t3 G

• Statement Verifier: Kanhaiya notsoloud1 Mohan

• Editorialists: Nishank IceKnight1093 Suresh

The written editorials will be available in the ‘Solutions’ tab of each problem once the contest ends

The video editorials of the problems will be available for all users for 1 day as soon as the contest ends, after which they will be available only to Pro users.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 51, this Wednesday, 10th August, rated for Div 2, 3 & 4 participants.

Time: 8 PM — 11:00 PM IST

Joining us on the problem setting panel are:

• Contest Admins: Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta

• Setters: Ashley errorgorn Khoo, Allen ijxjdjd, Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta, Hriday the_hyp0cr1t3 G, Yash kulyash Kulkarni, Abhinav abhi_inav Gupta

• Testers: Abhinav abhinavvv306 Sharma, Venkata Nikhil Nikhil_Medam Medam

• Statement Verifier: Nishank IceKnight1093 Suresh

• Editorialists: Nishank IceKnight1093 Suresh

The video editorials of the problems will be available on our YouTube channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Also, if you have some original and engaging problem ideas and are interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s July Long Challenge Two, starting this Friday, 22nd July, 3 PM IST onwards.

Please note, the contest is open for 3 days, i.e, from 22nd — 25th July. The Long Challenge Two will be rated for Div 3 & 4 coders.

Joining me on the problem setting panel are:

• Contest Admins: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta

• Setters: Jeevan JeevanJyot Jyot Singh, Utkarsh Utkarsh.25dec Gupta, Gheorghies Gheal Alexandru, Manuj DarkSparkle Nanthan, Abhinav Gupta

• Testers: Jatin rivalq Garg, Tejas tejas10p Pandey

• Statement Verifier: Nishank IceKnight1093 Suresh

• Editorialists: Devendra _Damon Singh

The video editorials of the problems will be available on our YouTube channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s Starters 45, this Wednesday, 29th June, rated for Div 2, 3 & 4 Coders.

Time: 8 PM — 11:00 PM IST

Joining us on the problem setting panel are:

• Contest Admins: Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta

• Setters: Valerio TheScrasse Stancanelli, Dinmukhamed DimmyT Tursynbay, Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta, Kishan kg1910 Gadhiya, Rudro Rudro25 Debnath, Abhinav Gupta

• Testers: Takuki tabr Kurokawa, Nishank IceKnight1093 Suresh

• Statement Verifier: Hriday the_hyp0cr1t3 G

• Editorialists: Yash kulyash Kulkarni

The video editorials of the problems will be available on our YouTube channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Also, if you have some original and engaging problem ideas and are interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating. Good Luck!

We invite you to participate in CodeChef’s June Long Challenge One , starting this Friday, 10th June, 3 PM IST onwards.

Joining me on the problem setting panel are:

• Contest Admins: Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta

• Setters: Kushagra koderkushy Goel, Muhammad Najmul Hasan nh_nayeem Nayeem, Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta, Lavish lavish315 Gupta, Satyam satyam343, Arun Arun_bro1 Sharma, Ashish Kryptonix Gangwar

• Testers: Takuki tabr Kurokawa, Lavish lavish315 Gupta, Abhinav abhinavvv306 Sharma

• Statement Verifier: Hriday the_hyp0cr1t3 G

• Editorialists: Devendra Dragon_warrior7 Singh, Yash kulyash Kulkarni

The video editorials of the problems will be available on our YouTube channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef’s contests, you can share them here.

Hope to see you participating.

Good Luck!

We invite you to participate in CodeChef’s April Long Challenge Two, starting this Friday, 22nd April, 3 PM IST onwards.

Please note, the contest is open for 3 days, i.e, from 22 — 25 April. The long Challenge One will be rated for Div 3 & 4 coders.

Joining me on the problem setting panel are:

• Contest Admins: Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta

• Setters: Aryan aryanc403 Choudhary, Siddhartha Tiwari sixth.sense1729, Prasant prasant21 Kumar, Devendra _Damon Singh, Jeevan Jyot JeevanJyot Singh, Utkarsh Utkarsh.25dec Gupta, Akash JustAkash21 Sharma, Hriday the_hyp0cr1t3 G

• Testers: Satyam satyam343 Kumar Roy, Aryan aryanc403 Choudhary

• Statement Verifier: Hriday the_hyp0cr1t3 G

• Editorialists: Devendra _Damon Singh, Daanish Mahajan

The video editorials of the problems will be available on our YouTube channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Also, if you have some original and engaging problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Hope to see you participating.

Good Luck!

Henlo Codeforces!

We are very glad to invite you to the Codeforces Round 754 (Div. 2), which will be held on 12.11.2021 17:35 (Московское время). This round will be rated for participants with a rating less than $$$2100$$$. For higher rated participants, we challenge you to solve problem F ;)

All the problems were authored and prepared by Ashishgup, the_hyp0cr1t3, ExplodingFreeze and me. We have tried our best to create an interesting problemset with clear statements. Hope you enjoy the round :D

You will be given $$$6$$$ problems and $$$2$$$ hours to solve them.

We would like to thank:

• antontrygubO_o for his amazing coordination and help in improving our problems.

• Our army of testers: Um_nik, 244mhq, Monogon, _runtimeTerror_, Jeel_Vaishnav, AmShZ, errorgorn, ijxjdjd, Utkarsh.25dec, Dragnoid99, yash_daga, Vivek1998299, taran_1407, MagentaCobra, Retired_cherry, sinus_070, AC_007, talibmohd, KahanHai, Dragonado, Submit_Galactic_Algo, KeyurJain, tvcv901, ekanshi, Jellyman102, jimmy18, inferno14 for testing the round and providing valuable feedback.

• MikeMirzayanov for the Codeforces and Polygon platforms.

Here's the scoring distribution of the round:

$$$500 - 1000 - 1500 - 2000 - 2500 - 3500$$$

UPD: Editorial is out

Also, congratulations to the winners.

Div 1 + 2:

1. SSRS_

2. Vercingetorix

3. MatikaneTannhauser

4. codinglunch

5. hank55663

Div 2:

1. MatikaneTannhauser

2. codinglunch

3. huyinghao0706

4. QuietBeautifulThoughts

5. MyBotDear

My friend the_hyp0cr1t3 and I came across this weird behaviour which we can't seem to explain.

The submissions 121761224 and 121761200 are identical, yet the former (submitted in C++17) gets accepted and the latter (submitted in C++14) gets WA on test 1.

After an hour of debugging, we managed to get it accepted in C++14 (121761314) with the following change in the code:

if(pos <= M) {
    lc = st[node].lc = create(lc);
    Update(lc, L, M, pos, val);
} else {
    rc = st[node].rc = create(rc);
    Update(rc, M + 1, R, pos, val);
}

if(pos <= M) {
    lc = create(lc);
    st[node].lc = lc;
    Update(lc, L, M, pos, val);
} else {
    rc = create(rc);
    st[node].rc = rc;
    Update(rc, M + 1, R, pos, val);
}

We would appreciate if someone could explain why something like a = b = c; and a = c; b = a; seem to produce different results.