Educational Codeforces Round 9

#	User	Rating
1	tourist	3985
2	jiangly	3814
3	jqdai0815	3682
4	Benq	3529
5	orzdevinwang	3526
6	ksun48	3517
7	Radewoosh	3410
8	hos.lyric	3399
9	ecnerwala	3392
9	Um_nik	3392

#	User	Contrib.
1	cry	169
2	maomao90	162
2	Um_nik	162
4	atcoder_official	161
5	djm03178	158
6	-is-this-fft-	157
7	adamant	155
8	awoo	154
8	Dominater069	154
10	luogu_official	150

Hello, Codeforces!

Today is the first day of the spring and it's great!

Educational Codeforces Round 9 will take place on 01 march 2016 at 18:00 MSK for the first and the second divisions. You can read about educational rounds here and here. I should again notice the high density of contests and championships.

The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

If you have ideas for some problems or maybe already prepared problems that you can't use in rounds or official competitions, you can write to me.

It seems that it is harder to invent interesting simple problems (like A and B) than difficult ones. So don't be afraid to suggest interesting simple or very simple tasks.

</This time it wasn't changed>

The problemset again was totally suggested by Codeforces users. The problem А again was suggested by user unprost (be ready to see a long problem statement). The problem D suggested by Denis Bezrukov pitfall. Alexey Chesnokov CleRIC sent the problem E a long ago. The problems B, C and F was suggested by Lewin Gan Lewin.

Thanks a lot to them and all others who are sending the problems or just ideas of the problems!

The problems was prepared by me (Edvard Davtyan). Thanks to Maria Belova Delinur for checking the English statements. The problems was tested by the same users who suggested them: unprost, Alexey Chesnokov CleRIC and Lewin Gan Lewin. Thanks a lot to all of them!

I hope you will enjoy the problems!

Good luck and have fun!

UPD1: The first part of the contest is finished. You can hack solutions.

UPD2: There are some technical problems. The phase of open hacks will be opened later (several hours).

UPD3: Editorial is ready.

UPD4: The contest is finished. We will start system testing in a few minutes.

UPD5: TOP3 of hackers:

P_Nyagolov — 31 hacks

khadaev — 27 hacks

halyavin — 23 hacks

Rev.	By	When	Δ	Comment
en7	Edvard	2016-03-02 20:20:40	39
ru10	Edvard	2016-03-02 20:20:11	3
en6	Edvard	2016-03-02 20:19:52	138
ru9	Edvard	2016-03-02 20:19:16	39
ru8	Edvard	2016-03-02 20:18:53	143
ru7	Edvard	2016-03-02 20:15:24	88
en5	Edvard	2016-03-02 20:14:54	152
ru6	Edvard	2016-03-02 03:35:17	88
en4	Edvard	2016-03-01 20:22:16	106
ru5	Edvard	2016-03-01 20:21:28	110
en3	Edvard	2016-03-01 20:03:20	76
ru4	Edvard	2016-03-01 20:01:27	80
en2	Edvard	2016-03-01 02:53:32	286
ru3	Edvard	2016-03-01 02:53:13	286
ru2	Edvard	2016-03-01 02:03:16	2	Мелкая правка: 'адиции будет предложе' -
en1	Edvard	2016-03-01 02:00:07	2246	Initial revision for English translation
ru1	Edvard	2016-03-01 01:23:52	2848	Первая редакция (опубликовано)

History