Codeforces Round #109(Div.2) report

It is a long time to see you!

I have participated in Round #109 for the first time since Round #101. I think, this round is Readforces.

A: This problem is good for grammar practice. If you can max and min from array, you can solve this problem. I accepted this (it is only AC on this contest), 488pts.

B: When I submitted first, I forget array's initialization. Resubmit twice, the source passed pretest. However , it's RE on test 19.

D: I can say nothing about this problem... Submit, pretest passed and hacked!

ox-x-,1005th/1683,488pts, Rate:1578->1501. I remained in blue barely.

Codeforces Beta Round #92(Div.2) report

This is Codeforces report after a long absence.

At first I decided to solve A. I misunderstanded it; 1WA.I resubmitted this at 00:08, and get Pretest Passed(and System test Passed).

I read B next, but it does not just occur to algorithm.Because there is no help for it, I move to C. However, Cdoes not understand meanings well either. Therefore Imoved to D when it was allocation of points same as C. D was good and understood a meaning, I took out graph paper and thought. I thought that it was the problem of a plus domain, the minus number domain, theimplementation was relatively comfortable when I was goodand thought. I submitted this at 1:08, and get Pretest Passed(and System test Passed).

I did not seem to be relieved of E, return chews it in C. I understood it , I got along well very much when I really crossed it.I submitted this at 1:35, and get Pretest Passed(and System test Passed).

o-oo-,Score:3130,Place:26/1458,Rating:1550->1666(Blue to Purple!) Problems are here.

Codeforces Beta Round #89(Div.2) & #90 Sources

Codeforces Beta Round #89(Div.2) & #90, My sources.

Only Source(ソースだけ)

This article is Only Source! I'm too busy now, so I can't write report.
本記事はソースのみです。忙しくて、レポートを書いている暇がないのでご了承ください。

There are sources which I made at the next contest.
次のコンテストで作成したソースです。

・Codechef September Long/Short
・Codeforces #87 (Div.2) / #88
・Topcoder SRM 518(Div.2)
・UVa The Seventh Hunan Collegiate Programming Contest Semilive
・UAPC 7th

Codeforces Beta Round #83 & #86 (Div.2) Report

I write about two competition because I haven't written codeforces #83.

<Codeforces Beta Round #83 (Div.2)>
Because I was tired, I could solve only one problem!

I solved A, at 00:04. And it's all of this contest.

B: I think the case is YES if Max of bit is smaller than twice of second-max. However, It's wrong at system test!

And then, I was very sleepy, and I began to be sleep.

Score=492, Standings=465/1179.

<Codeforces Beta Round #86 (Div.2)>
I think I'm slumpa now!

A: I didn't understand first, however, second reading made me to understand. I solved at 00:04, and it is all accepted of this contest.

B: I read and tried to solve. I submitted, and WA on pretest. Then, I notice my reading miss. So, I gave up this. If you want to know how I made miss, please read source.

C: I solved, however, I forgot
"A sentence is either exactly one valid language word or exactly one statement.".
So, I get WA. I get accepted after the contest, and the source is correct source.

E: I think, it is Fermat's 4N+1 theorem. I write my code very simply, it was TLE. If I had more time, I try other algorithm.

Score=492, Standings=377/1337, Rate:1418->1452.
This contest was a little difficult??

Codeforces Beta Round #85(Div.2) report

I think this contest's problems are very good because it's short! And I submitted all problem! I think, it's my first "all-problem-submitted contest". However,  only two sources were accepted because I have careless misses.

A: I solved this 0:07. Using strcmp.

B: I solved this 0:17. A little thinking, we get very simple answer.

C: I solved this 0:39. However, I don't see y<n case. So it's hacked, and I solved after contest. Algorithm is good.

D: I solved this 0:56. However, I use unsigned short, and I should use unsigned int. So, WA at System test. I solved after contest.Algorithm is good, too.

E: I submitted this, but I can't get good algorithm.

Problems are here.
Result:1418,442/1273. Rate 1419->1418.
If you want to know C or D's algorithm, please read my source!

I'm going to write Codeforces #83's report next.

Codeforces Beta Round #82(Div.2) report

My score is a little bad, however, I enjoy this contest very much!

I drank tea with friends, so I started this contest 0:15.

I made A, and got accepted at 0:27 with 2 submits.

I think B is not difficult, however, I had easy miss. I got accepted at 0:48 with 4 submits.

I read C and I don't want to solve it because I didn't  practice such problems enough. So, I read D and E, I decided to solve E.

I thought E is similar to least squares method, however it's not! I notice that point at 1:30, and I thought another method. But, time was over!

Now I think, E can be solved with downhill simplex method.

Problems are here.

Score:1104,Rank:541/1340,Rate:1504->1451.

I need more and more practice!

Codeforces Beta Round #81 report

It's too bad!

I read Problem-A, first. I solve this, and test first at 0:20.
However, I notice lexicographical order. So, I make sort. Submit at 0:35. And System test, there is round-off error. I'm wrong!

Other problems, I gave up because...
1. It's difficult for me!
2. The problem is too long! I'm not good at English, so it's hard.

Then, Score=0. Rank=403/1500. Problems are here.
No people could solve all problems, and about 1100 people couldn't solve any problem.
I think, this round is difficult.

Codeforces Beta Round #80(Div.2) report

I submitted four, however I accepted two. It's bad score! Fortunately, my rank is still blue.

A: I listed answers with switch. This problem's inputs exist only 25 way. Submit and pretest passed at 0:05.

B: I was tired because I have some work before this contest. So, I can't concentrate this problem. I get a formula, and I submit, pretest passed at 0:25.

E: I think this problem is only calculating sum which is part of the sequence. However, I can't get good algorithm. I had many TLE(1:20).

D: I couldn't understand this. So, I anticipated the answer from samples. Surprisingly, I get pretest passed at 1:54 (of course, it's wrong!). This pretest is crude!

I get 1398,310/1093. Problems are here.

This round problems are difficult. Because Div.1 A=Div.2 B,1B=2C,1C=2D,1D=2E.

Codeforces Beta Round #79(Div.2) Report

I feel frustrated.

A:I had some reading miss.However, 0:24,Pretest Passed.

B&C, all i have to do is coding. B,0:39 and C,0:57,Pretest Passed.

I also can solved E. 1:33,Pretest Passed. However, this source occurred overflow. So, I use 64-bit integer, it's correct(after contest). In this article, E's source is correct.

I explain E's algorithm.

Regard vectors A,B,C as complex number. Then, rotate or add C, we can get next number.

i(i(i(i…(i(A+n1C)+n2C)+n3C)+…)+nkC

Calculate it and use i^2=-1,

(i^m)A+NC+iN'C

is equals to B. (m=0,1,2,3)

Then,

B-(i^m)A=CN+iCN' .

Solve this eq. about N,N'. If they are Integer, Yes. 

Result:2404,216/1015.This round show a little easy.

Codeforces Unknown Language Round #3 Report

It's special contest! Congratulation to Codeforces because they make 100th contest!

[Rule]
We can submit your code using only one language. This language is a secret and will be announced only when the contest begins!
-> The language we can use is Pike7.8. The language isn't rank in TIOBE.

[Report]
Start, I get compiler. I use Ubuntu Linux 11.04, so I can install with next command.

sudo apt-get install pike7.8

And read tutorials(here). I can join this contest only two hour, so I think it's good I can get two accepted.

A: Use read function and cast. I got accepted 0:43.

• I couldn't find how to input integer. So, read and cast.
• Fortunately, if we cast string to integer, it works as C's atoi function.

C: Use string. I got accepted  1:54.

• We can get n-th character of string s with s[n] (0-offset). However, it's int.
• So,  s[n]-'0' means the number s[n] of int.

Result, Penalty=177, Standings=155/805.

I expect to hold next Unknown language round!

Codeforces Beta Round #78(Div.2) report

(This article is not explanation but my report. Please understand my aim.)

This contest, I get my really score, I think.

A: Once read miss, once coding miss and twice type misses. So, I solve this at 00:23, score=254. It's worst score of A, which I can solve.

B: Accepted with only once submit at 00:36. Score=856. I thought I should solve this first.

C: First Pretest-Passed at 01:03, however it was hacked. So, I search this, and I read here(Japanese). I solved at 01:47 finally. Score=808. However, it is wrong at system test. The miss is my writing miss.

I read D and E, however it's too difficult for me to solve. I'm going to read D's Editrial and solve this.

Result,1110,323/1219. I think this score is a little good for me. And I'd like to practice programming more and more.

Codeforces Beta Round #77(Div.2) report

There is a recorder ensemble concert immediately before, and after I performs to it, took part in the contest. I thought I shouldn't take part in it. So, the result isn't so good.

I started to solve problem A, however, I can't read the problem because network error. I thought I'll stop to join this, but I can read at 0:03. I solved it at 0:08.

Problem B. It has something hard to me. So, I solved at 1:50. I spent too much time! However, I thought I couldn't solve Problem C,D or E, because I couldn't understand the problems' mean.

487/1121,Score=486.Problems are here.

Codeforces Beta Round #76(Div.2) report

It's my top score contest!

After starting, I get accepted Problem A(10min). It's very simple problem.

I start problem B.Wrong answer twice(0:19,0:21). I found my wrong in reading, I get accepted(0:22).

Problem C。It's a problem about select folders. I like this problem, it's interesting! I submitted wrong answer twice, however I found a miss, I get accepted(0:42).

It is happy to be able to solve Problem D. Once I read this problem, I think this is greedy algorithm.  Surprisingly, I accepted this only one submit(1:18).

I can't solve Problem E in programming time.

Problems is here。3816,8/1070. It's excellent! I'm grad and celebrate this. I'm ranked up to blue.