My last two-month training before NOI(Chinese National Olympiad of Informatics)

Revision en3, by King_George, 2017-05-06 12:17:44

Just several hours ago, JSOI2017(the selection contest in my province) ended, and I ended up with rank 5. Finally, I could go to NOI(Chinese National Olympiad of Informatics, more details can be found here), which will be held in July. Although rank 5 is pretty good, there's still a wide gap between top 4 and me(congrats to the top 4 who may get a 5-point bonus in NOI). This means I have to learn more and train harder, so here comes the post. In this post, I'm gonna record my daily training and contests during the last two and a half months. I hope keeping updating will push me to train harder and also improve my English in the same time. The problems mentioned here may be easier than those mentioned in matthew99's and Petr's blog, but I'll do my best to make this post great. Hope you may like it. :)

Codeforces Round #411 will start in less than one hour. I'll make my first record after it. Wish everyone good luck.

My performance in the contest was a complete flop. I was too sleepy to code problem C and D, though they were not too difficult. I was exhausted after the two-day provincial-team-selecting contest. Maybe all I need now is just a good rest. I will solve the problems left in the contest after that and share with you later.

May 6th

I solved problem B of Petr Mitrichev Contest 1. The problem is not too difficult. The key is that if we know the value of A(1, j) and A(i, 1), then we can calculate all A(i, j). Then the problem becomes whether there exists some values of A(1, j) and A(i, 1) such that all A(i, j) is between 0 and 1. For two elements A(i, 1) and A(1, j), we have some limits that it's impossible for A(i, 1) = x and A(1, j) = y simultaneously. So the problem becomes a 2-SAT.

#### History

Revisions

Rev. Lang. By When Δ Comment
en17 King_George 2017-05-22 06:30:20 478
en16 King_George 2017-05-21 02:55:23 272
en15 King_George 2017-05-19 16:01:52 208
en14 King_George 2017-05-18 16:29:53 344 (published)
en13 King_George 2017-05-18 04:52:55 98 (saved to drafts)
en12 King_George 2017-05-17 16:53:38 2347
en11 King_George 2017-05-15 19:28:54 2005 Tiny change: 'ting at \$j\$(i < j <= ' -> 'ting at \$j(i < j <= '
en10 King_George 2017-05-14 15:24:14 1021
en9 King_George 2017-05-12 03:40:43 691
en8 King_George 2017-05-11 17:21:55 893
en7 King_George 2017-05-10 13:15:57 975 Tiny change: '99] using _**FFT**_' -> '99] using **FFT**__'
en6 King_George 2017-05-09 17:27:12 666
en5 King_George 2017-05-08 04:38:46 122
en4 King_George 2017-05-07 04:00:11 1099
en3 King_George 2017-05-06 12:17:44 540 Tiny change: '1, j) = y\$. So the p' -> '1, j) = y\$ simultaneously. So the p'
en2 King_George 2017-05-05 08:53:34 326
en1 King_George 2017-05-04 16:48:01 1088 Initial revision (published)