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26.06.2016. The Rust Programming Language was added
Rustc compiler version 1.9.0 was added. For more details on how to solve problems using Rust read the help page. Thanks to Alexander Savelyev for his assistance.
27.04.2016. New problem 1896 War Games 2.1
New problem 1896 was added to the problemset. It is the same problem as 1521, but with bigger limitations. The problem was prepared by Maxim Pivko.
27.09.2015. New problem 1799 Sasha and swag strings
New problem 1799 was added to the Problem set. The problem was prepared by Alexander Kulkov.
23.09.2015. New problem 1599 Winding Number
New problem 1599 was added to the Problem set. The problem was prepared by Vladimir Yakovlev.
22.09.2015. Compiler updated
Visual C++ 2013 is now available. It's command line is the same as it was in Visual C++ 2010. However, the exit code of the program must be zero.
21.09.2015. Solutions are judged on a new server
Since September 1, 2015 solutions are judged on a virtual machine with an Intel Xeon E5-2665 2400 MHz processor running Windows 7 SP1 32-bit.
2.08.2015. New problem 1798 Fire Circle. Version 2
New problem 1798 was added to the problemset. It is the same problem as 1490, but with bigger limitations.
3.10.2014. Compilers update
The following compilers were updated:
  • MinGW GCC 4.9.1. Like before it’s available in four configurations. New: the programs are linked against libmsvcr110 instead of libmsvcrt. That allows you to use for example the specifier %lld rather than %I64d.
  • Clang 3.5 (new). Available only in the C++14 mode. More about MinGW GCC and Clang
  • FreePascal 2.6.4. More about FreePascal
  • JDK 8.0. More about Java
  • Scala 2.11.2. Works on top of the JDK 8.0. More about Scala
  • Python 2.7.8 and Python 3.4.1. New: exit function call doesn’t result in Runtime error. More about Python
For all of these compilers the exit code of the program is now checked. A non-zero exit code will result in the judging result Runtime error (non-zero exit code).
11.09.2014. New problem 1598 DSA Attack
New problem 1598 was added to the Problem set. The problem was prepared by Vladimir Yakovlev.
4.09.2014. Go language compiler was updated to version 1.3.1
Since there is no degradation when migrating from Go 1.1 to Go 1.3.1, the new compiler will be used for rejudgung old submissions.
2.09.2014. The problems 1012 and 1013 (K-based Numbers, Versions 2 and 3) are reworked
Problems 1012 and 1013 were very similar, and were accepted with the same solution in most cases. Recently a new version of this problem has been offered. It was decided not to add yet another version of the problem, but to replace one of the existing versions. Thanks to Egor Schelkonogov for preparing the new problem!
  • The limitations in the problem 1012 to the sum of N and K were changed from 180 to 1800 (as it was in the problem 1013).
  • The new limitations (up to 1018) and input/output format were set in the problem 1013.
  • All submissions to the problem 1013 were moved to the problem 1012.
  • The time limit for both problems is set to 500 ms.
19.08.2014. New problem 1597 Chernobyl’ Eagle on a Roof. Version 2
New problem 1597 was added to the Problem set. Thanks to Sergey Vedernikov.
15.09.2013. Changes in problem 1004 Sightseeing Trip
  • Limitations in the problem statement were changed: now N ≥ 3 (old limitation was N ≥ 1); 3 ≤ MN · (N − 1) (old limitation was 1 ≤ M ≤ 10000); length of the road ≤ 300 (old limitation was length of the road < 500).
  • New limitation was added: 1 ≤ T ≤ 5, where T is a number of test cases (there was T ≤ 10 in the old test set, but the problem statement didn't contain this limitation).
  • All tests were fixed according to the new limitations, and some new tests were added. The first test now is a sample test from the problem statement.
  • Time limit was decreased to 0.5 sec.
11.05.2013. Changes in problem 1400 Cellular Characters
  • Bugs in checker were fixed.
  • New limitation was added to the problem statement: M ≤ N. Tests not satisfing this limitation were removed.
  • New tests were added.
All submissions were rejudged.
22.04.2013. Changes in problem 1500 Pass Licenses
  • Clarification in problem statements: For any pair of crossroads no two segments of the same category connect these crossroads.
  • Tests not satisfing this condition are corrected.
  • The first test is changed to the sample from the problem statements.
  • New time limit is 2.5 seconds (old time limit was 3 seconds).
  • New memory limit is 64 MB (old memory limit was 16 MB).
  • New tests are added
All solutions are rejudged. More than 100 authors lost AC during this rejudge.
29.03.2013. Problem 1005 Stone Pile. Tests added
  • New tests have been added.
  • First test is now the sample from the problem statements.
  • Memory limit is changed from 16 MB to 64 MB.
  • Time limit is changed from 2 seconds to 1 second.
Solutions have been rejudged. More than 1700 authors have lost AC.
27.03.2013. Memory limits correction for old problems
Memory limits were corrected for most of old problem where it was set to 16 MB. The new memory limit for these problems is set to 64 MB.
24.03.2013. Scala programming language added
Compiler Scala 2.10.1 (JDK 7) added.
18.02.2013. New compilers added
New compilers added:
  • Go 1.0.3
  • VB.NET 2010
  • Python 2.7
  • Python 3.3
  • Ruby 1.9.3
  • Haskell 7.6.1
  • MinGW gcc 4.7.2
  • MinGW g++ 4.7.2
18.01.2013. The Java compiler updated to JDK 7
The Java compiler was updated to JDK 7.0 Update 11. Previous compiler will be used for rejudging old submissions only.
4.10.2012. Changes in problem 1410 Crack
The following limitations were added:
  1. The phrase doesn't contain two equal words (the case of letters should be ignored).
  2. The amount of words in one phrase doesn't exceed 10000. (Old limit was 100000, but there was no tests with amount of words greater than 10000.)
  3. Total input size doesn't exceed 512 KB.
Some new tests were added, the problem was rejudged.
25.09.2012. New problem 1797 Summit Online Judge. Version 2
New problem 1797 was added to the Problem set. Thanks to Xie Lingxi.
23.07.2012. Bug with BigInteger.isProbablePrime is solved now
An error, which caused "Restricted function" verdict on Java solutions used "BigInteger.isProbablePrime" method, is fixed now. Details at forum. All solutions with this verdict are rejudged now.
9.03.2012. New problem 1596 Knight Mare
New problem 1596 was added to the Problem set. Thanks to Vladimir Basunkov.
27.02.2012. Now you can filter the rating of solutions by the programming language
From today you can filter the rating of solutions by the programming language. This is especially important if you solve problems in Java or C#, for which the minimum work time of a solution is higher than for example C++. If you have solved the problem in several programming languages​​, then your best solution for each language will be shown in the appropriate filtered rating, and best of all solutions will be shown in the overall ranking.

To open the rating of solutions, click on the link at the bottom of the problem statements page.
15.12.2011. Changes in problem 1052 Rabbit Hunt
  1. |x|,|y| ≤ 2000 (|x|,|y| ≤ 1000 in the old version, but some tests didn't satisfy this limitation).
  2. N ≥ 3 (N ≥ 2 in the old version, but there was no tests with N = 2).
  3. There was a single zero in the last line of input in some tests. These tests were fixed.
  4. In one test some positive numbers had leading zeroes. Leading zeroes were deleted.
  5. New TL is 1 second (old TL was 2 seconds).
  6. New tests were added
Before adding new tests all solutions with verdict TL and with verdicts WA and Crash on incorrect tests were rejudged. Some solutions got AC verdict. After adding new tests all solutions with verdict AC were rejudged. More than 400 authors lost AC during this rejudge.
23.11.2011. Changes in problem 1029 Ministry
Now the fee is a positive integer (it could be equal to zero in the old version). Tests with zero fee were fixed. New tests were added. 41 authors lost AC, 2 authors got AC.
14.11.2011. Problem 1145 Labyrinth. Tests added
Some tests with n ≠ m were added. 113 authors lost AC.
12.11.2011. Problem 1120 Sum of Sequential Numbers. Tests added
New tests have been added. 89 authors have lost AC after rejudge. Thanks to Alexey Zolotov for sending the tests.
9.11.2011. Problem 1027 D++ Again has been rejudged
New tricky test was added, and all AC submissions were rejudged. 96 authors lost AC. Thanks to Fyodor Menshikov for this test.
9.11.2011. Problem 1036 Lucky Tickets. Tests added
New tests have been added. 146 authors have lost AC after rejudge.
1.11.2011. Problem 1332 Genie Bomber. Tests added
New tests have been added. 73 authors have lost AC after rejudge. Thanks to Konstantin Bulatov for sending the tests.
12.05.2011. Problem 1394 Ships. Version 2. New tests
New tests were added to the problem testset. Accepted solutions were rejudged. None of them passed all of the new tests. Thanks to Maxim Buzdalov.
25.01.2011. Changes in problem 1315 MDPAR and MIIAR
The limitations in the problem statement were decreased. New limitations are W, H ≤ 500; D ≤ 1000. Tests were fixed according to these limitations. New tests were added. All submits were rejudged. 5 submits got AC verdict, 41 submit lost AC verdict. Thanks to Sergey Vedernikov and Roman Rizvanov for new tests.
7.01.2011. Problem 1034 Queens in Peaceful Positions. Tests added
New tests have been added. 50 authors have lost AC after rejudge.
5.01.2011. Problem 1220 Stacks. Tests added
New tests have been added. 187 authors have lost AC after rejudge.
5.01.2011. Problem 1302 Delta-wave. Tests added
New tests have been added. 153 authors have lost AC after rejudge.
7.11.2010. Problem 1058 Chocolate. Tests added
New tests have been added. 88 authors have lost AC after rejudge. Thanks to Fedor Fominykh for these tests.
7.11.2010. Changes in problem 1058 Chocolate
The input format was changed:
  • Vertices are listed in the counter-clockwise order.
  • Coordinates are given with at most 3 digits after decimal point.
All tests that didn't satisfy these conditions were fixed (including sample test). Some tests contained polygons with 180 degree angles. They were fixed too.
9.09.2010. Problem 1170 Desert. Validator program fixed
There were bugs in validator program. They were fixed and the problem was rejudged. 299 WA submits turned to AC and 84 AC submits turned to WA. Thanks to Eugene Kurpilyansky who found bugs and helped to fix them.
16.08.2010. Problem 1627 Join. Statement updated
The following sentence is added:
It is guaranteed that there is at least one bedroom in the house.
4.08.2010. C# Compiler Upgraded to Visual C# 2010
The C# compiler was updated to Microsoft Visual C# 2010 (.NET Framework 4.0). For rejudging of old C# submissions the compiler that was in the system in the moment of submission will be used.
3.08.2010. C/C++ Compiler Upgraded to Visual C++ 2010
The C/C++ compiler was updated to Microsoft Visual C++ 2010. For rejudging of old C/C++ submissions the previous compiler will be used. You can download a free copy of Microsoft Visual Studio 2010 Express on this page. To learn about key features of the new compiler go to this help page.
13.05.2010. Problem 1421 Credit operations. Statement updated
The following sentence was added:
The sum of all SR[i] is equal to the sum of all SC[j].
12.05.2010. Problem 1099 Work scheduling. Tests added
New tests have been added to defeat different wrong algorithms. The order of the tests have been changed. 91 authors have lost AC after rejudge. Thanks to Sergey Kopeliovich for new test set.
20.04.2010. Problem 1209 1, 10, 100, 1000... Tests added
New tests have been added to this problem. Previously accepted solutions have been rejudged. 196 authors have lost AC.
19.04.2010. Problem 1195 Noughts and Crosses. Statement updated
Following sentences were added to the input format:
The table contains exactly three Crosses and three Noughts. It is guaranteed that the game is not finished, i.e. any row, column or diagonal contains neither three Crosses nor three Noughts.
16.04.2010. Changes in problem 1248 A sequence sum
Some bugs in validator were fixed. New tests were added. The problem was rejudged.
30.12.2009. Timus Online Judge comes back
After a three-week break Timus Online Judge resumed its work. During this time our broken servers were repaired. In addition the web server is now working on a new place with a different IP-address. The feature of the new hosting is that the command "ping acm.timus.ru" will not work.

Site Administration welcomes all who come to us again! Happy New Year!
8.09.2009. Problem 1695 Work for Robots. Tests added
New tests have been added to this problem against inefficient solutions. Previously accepted solutions have been rejudged. 15 authors have lost AC. Thanks to Maxim Buzdalov for the set of new tests.
24.08.2009. Changes in problem 1223 Chernobyl’ Eagle on a Roof
The following changes were made in the problem statement:
  • This sentence was added: If an egg has been broken being dropped from the first floor, you should consider that E is equal to zero.
  • The number of eggs is positive and does not exceed 1000.
  • The number of test cases in the test does not exceed 1000.
  • The last line contains two zeroes, not one (it corresponds to the problem tests). Sample input is fixed.
New tests were added. 157 authors have lost AC after rejudge.
24.08.2009. Problem 1212 Battleship. Statement updated
The following sentence is added:
Ships may have from one to four decks.
10.08.2009. Problem 1038 Spell checker. Tests added
New tests have been added to this problem. Solutions have been rejudged. 564 authors have lost AC.
8.08.2009. Problem 1085 Meeting. Statement updated
1) This phrase has been removed from the problem statement:

some money is to be left for the party

2) This phrase has been fixed:

old version:
there is a non-negative integer in the beginning of a line that is an amount of money (in rubles) the person has

new version:
there is a positive integer in the beginning of a line that is an amount of money (in rubles) the person has
26.07.2009. Problem 1589 Sokoban. Tests added
New tests have been added to this problem. Solutions have been rejudged. 6 authors have lost AC.
20.07.2009. Problem 1099 Work scheduling. Tests added
New tricky tests have been added. 104 authors have lost AC after rejudge.
18.07.2009. Problem 1136 Parliament. Statement is fixed
Limitation for identification numbers is fixed and equal to 65535, corresponding to the test set.
18.06.2009. Problem 1394 Ships. Version 2. New tests
New difficult tests were added to the problem testset. Previously accepted solutions were rejudged. None of them resisted. However, the fact that the problem is NP-complete doesn't mean that it is impossible to write a solution which passes only a few dozen of tests. Thanks to Maxim Buzdalov for making this set of tests.
12.06.2009. Problem 1244 Gentlemen. Statement updated
It's guaranteed that the total weight of all cards in the complete pack is strictly greater than the weight of the incomplete pack.
7.06.2009. Problem 1369 Cockroach Race. Tests added
New tests have been added. Time limit increased to 5 seconds. All solutions have been rejudged. Most authors have lost AC after rejudge.
7.06.2009. Problem 1363 Halftones. Validator program fixed
There was a bug in validator program, and many wrong solutions got Accepted because of it. Besides, during investigation of this problem we decided to change the number in the inequality in the problem statement from 30 to 20.
3.06.2009. Problem 1151 Radiobeacons. New tests added
New tests have been added. 78 authors have lost AC after rejudge.
3.06.2009. New problem 1595 Perfect Sequence
New problem 1595 was added to the Problem set. Thanks to Aleksandr Bacherikov.
27.05.2009. New problem 1594 Aztec Treasure
New problem 1594 was added to the Problem set. Thanks to Igor Chevdar, the author of this problem.
12.05.2009. Ural Championship 2001. Russian versions of statements added.
Problems 1149-1157 now have both English and Russian texts. If you find some mismatches betweeen these two versions, please, write to timus_support (at) acm.timus.ru.
10.05.2009. Problem 1045 A funny game. New tests added
New tests have been added. 325 authors have lost AC after rejudge.
29.04.2009. Problem 1357 Teakettle 1.0 for Dummies. Tests corrected
Test #17 has been corrected, solutions that had troubles with this test have been rejudged. 15 authors have got AC.
15.04.2009. Changes in problem 1307 Archiver
  • Time limit was changed from 2 seconds to 1 second;
  • Memory limit was changed from from 2 MB to 4 MB;
  • Validating program was corrected, sometimes it gave wrong verdicts;
  • One more test was added.
All solutions have been rejudged.
9.04.2009. Problem 1274 Fractional Arithmetic. New tests added
New tests have been added. Accepted solutions have been rejudged. 295 authors have lost AC after rejudge.
16.03.2009. Changes in problem 1435 Financial Error
The limitation on N is reduced from 1500000 to 200000. The time limit is reduced from 2 seconds to 0.4 seconds. Tests that do not meet the new limitations are removed. New tests for various tricky cases are added. All solutions have been rejudged.
22.02.2009. You can download your solutions now
You can no longer keep your solutions. You will always be able to download them directly from our site. See details on the frequently asked questions page.
13.02.2009. C# language changes
  • The default decimal separator was changed from comma to point.
  • Conditional compilation symbol ONLINE_JUDGE was added.
C# submissions which worked with floating-point numbers in input/output or ONLINE_JUDGE symbol were rejudged.
12.02.2009. Help section about C# language added
Due to high demand new section was added to the frequently asked questions: how to write C# solutions.
11.02.2009. Changes in problem 1299 Psylonians
There were mistakes in English version of problem statement. Following changes were made:
  1. According to the “Defense” pattern, robot’s actions are defined as follows: calculate the number of enemies and multiply it by 20. If the result is NOT LESS than the amount of ammunition units left, the robot will “Retreat and Return Fire”. Otherwise, it will act as if following the “Guard” pattern.
  2. Similarly, when the battle-robot “Advances and Returns Fire”, it checks the angle to the most dangerous enemy. If the angle is 10 degrees or more, or there are no enemies, the robot just moves FORWARD or shoots otherwise.
  3. Angle values range from -179 to 180 inclusive, all other integers are non-negative and none of them exceeds 1000.
Some tests were added. The problem was rejudged. We apologize to all authors who solved this problem using old incorrect English statement.
8.02.2009. The C# compiler updated to Microsoft Visual C# 2008
The C# compiler was updated to Microsoft Visual C# 2008 version 3.5.30729.1 (.NET Framework 3.5). Previous compiler Microsoft Visual C# 2005 will be used for rejudging old submissions only.
5.02.2009. Changes in problem 1190 Bar of Chocolate
There are following changes in problem statement:
  1. The name of the component is no longer than 16 symbols (old limitation was 30).
  2. All the components have different names.
  3. All specified weight fractions are given in non-increasing order.
  4. Real weight fractions are integers from 1 to 10000 (in hundredths of percent).
All tests with equal component names are fixed. New tests were added. The problem is rejudged.
4.02.2009. New problem 1593 Square country. Version 2
New problem 1593 was added to the Problem set. It has the same problem statements as in the problem 1073, but with bigger limitations. Thanks to Fyodor Menshikov for the idea and the implementation.
3.02.2009. Problem 1306 Sequence Median. Statement updated
Now each element of the sequence is a positive integer not greater than 231−1 inclusive (old limitation was 232−1).
3.02.2009. The property ONLINE_JUDGE is now defined for Java programs
Java programs are executed with argument -DONLINE_JUDGE now. This feature can be used to detect whether your program runs on the server or it runs on your machine.
See details in this help section.
2.02.2009. The Java compiler updated to JDK 6
The Java compiler was updated to JDK 6.0 Update 11. Previous compiler JDK 5.0 will be used for rejudging old submissions only.
24.01.2009. Problem 1257 Hyphenation. Statement updated
Now limitation for number of lines in the text is 450 (old limitation was 1000). This limitation corresponds to the current test set.
22.01.2009. Problem 1328 Fireball. Statement updated
Now limitation for N is N ≤ 10. This limitation corresponds to the current test set.
22.01.2009. Problem 1334 Checkers. Tests added
New tests have been added. Many authors have lost AC after rejudge.
20.01.2009. Problem 1560 Elementary symmetric functions. Tests corrected
Incorrect test #16 has been corrected. All solutions that had troubles with this test have been rejudged.
20.01.2009. Problem 1351 Good Gnusmas – Dead Gnusmas. Tests added
New tests have been added. Many authors have lost AC after rejudge.
18.01.2009. Problem 1203 Scientific conference. New tests
New tests were added. 212 authors lost AC after rejudge.
10.01.2009. Online contest "Ural SU contest. Petrozavodsk training camp. Summer 2008" has finished
Congratulations to the winners!
  1. Blue Mary
  2. Yerzhan_Utkelbayev
  3. Bruce Merry
  4. QiZiChao
  5. Anton Lun'ov
  6. double
  7. Ostap Korkuna (Lviv NU)
  8. Solej
  9. hark&Jby_Yeah
  10. acrt
Onsite contest results are available here.
5.01.2009. Problem 1073 Square country. New tests
New tests were added. 187 authors lost AC after rejudge.
3.01.2009. Problem 1226 esreveR redrO. New tests
New tests were added. All AC solutions were rejudged.
3.01.2009. Problem 1146 Maximum Sum. New tests
New tests were added. 556 authors lost AC after rejudge.
3.01.2009. Problem 1283 Dwarf. Statement updated
Section "Input" has been updated. Now limitations for all numbers in the input data are given (all limitations correspond to the current test set).
28.12.2008. Problem 1040 Airline company. Tests corrected
Test #13 has been corrected, solutions that had troubles with this test have been rejudged. 23 authors have got AC.
24.12.2008. Problem 1216 Two Pawns and One King. Statement updated
Problem statement has been updated. This phrase has been added:
White moves first.
14.12.2008. Problem 1423 String tale. Statement updated
Problem statement has been updated. This phrase has been added:
Each string has length N
11.12.2008. Problem 1043 Cover an Arc. New tests
New tests were added. AC verdicts of 93 authors turned to WA.
11.10.2008. Online contest USU Championship 2008 has finished
Congratulations to the winners!
  1. [SPbSU ITMO] WiNGeR
  2. Zodiac
  3. Nick J
  4. Belarusian SU #2
  5. SUrSU Thinkers
  6. crdp
  7. Saratov SU2: Klenov, Rakhov, Ivanov
  8. DonNU Team (Lunyov, Kuzovkov, Lomonos)
  9. Jia Zhendong
  10. Ufa SATU TeamSonic: Akhmetzyanov, Nefyodov, Maryin
  11. Dirichlet
Onsite contest results are available here (in Russian).
9.10.2008. New server for solution checking has been installed
Since 13.00 October 9, 2008, solution checking has been moved to a new server. Server configuration:
  • processor: Core 2 Quad Q6600 (frequency 2400 MHz, L2 cache 8 MB, bus frequency 1066 MHz);
  • memory: 4 GB;
  • HDD: Seagate Barracuda 7200.10 250 GB;
  • operating system: Windows XP SP3.
Time limits for most of the problems will be corrected in the near future. Old solutions will be rejudged. All upcoming contests will be held on the new server.
8.10.2008. News section has been created
News section has been created. Some old news will be moved from the Webboard to this section.
13.09.2008. Problem 1148 Building Towers. Statement updated
Problem statement has been updated. All ambiguities are eliminated.
9.09.2008. Problem 1231 Turing: One, Two, Three. Validator program fixed
Validator program has been fixed. Problem has been rejudged. 6 authors lost AC.
28.06.2008. Problem 1178 Akbardin’s Roads. Statement updated
Russian statement has been updated and now corresponds to English one. This line has been added:
Никакие три города не лежат на одной прямой.
It corresponds to English
No three towns lay on one line.
13.05.2008. Problem 1130 Nikifor’s walk. Tests added
A new set of tricky tests has been added to this problem. 59 authors have lost AC after rejudge.
5.05.2008. Problem 1071 Nikifor 2. Tests added
New tests have been added. 15 authors have lost AC after rejudge.
23.04.2008. Java compiler upgrade
Java compiler has been upgraded from JDK 5.0 Update 6 to JDK 5.0 Update 15.
20.03.2008. Problem 1245 Pictures. Tests corrected
Tests 7 and 8 containing spots with negative coordinates of center has been fixed. Problem has been rejudged.
13.02.2008. Problem 1412 Autumn tide. Tests added
New tricky tests have been added. Many authors have lost AC after rejudge.
28.01.2008. Problem 1589 Sokoban. Tests added
New tricky tests have been added to this problem. Solutions have been rejudged.
21.11.2007. C/C++ Compiler switches changed
Switch /O1 was added to command line of C/C++ compiler. This switch is used instead of default /O2 switch. Description from compiler help:
  • /O1 – optimize for maximum speed, but disable some optimizations which increase code size for a small speed benefit
  • /O2 – optimize for maximum speed (DEFAULT)
ICL compiler sometimes makes wrong code with /O2 switch. To prevent wrong verdicts we have changed switches but loose some performance. Some programs will work a little bit slower now. Current compiler’s command line:
  • For C:
    icl /GX /TC /Za /O1 /D ONLINE_JUDGE
  • For C++:
    icl /GX /TP /Za /O1 /D ONLINE_JUDGE
(See this help page)