Codeforces Round 1080 (Div. 3)

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ContestId
Name
Phase
Frozen
Duration (Seconds)
Relative Time
Start Time
2195 Codeforces Round 1080 (Div. 3) FINISHED False 9000 5238923 Feb. 15, 2026, 2:45 p.m.

Problems

Solved
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Name
Type
Tags
Community Tag
Rating
( 452 ) H Codeforces Heuristic Contest 001 PROGRAMMING brute force constructive algorithms geometry implementation

There is a grid of (3n \times 3n) points, consisting of all integer points ((x,y)) such that (1 \le x,y \le 3n). Find a largest set of triangles satisfying the following conditions: Each triangle has its vertices on exactly three points on the grid. Each triangle has an area of exactly (\frac{1}{2}). Note that they do not have to be right triangles. No two triangles share a common intersection point, including their vertices. If there exist multiple largest such sets of triangles, you may output any of them. Each test contains multiple test cases. The first line contains the number of test cases (t) ((1 \le t \le 30)). The description of the test cases follows. The only line of each test case contains a single integer (n) ((1 \le n \le 166)). It is guaranteed that the sum of (n^2) over all test cases does not exceed (166^2). Output the maximum size (m) of the set of triangles on one line ((0 \le m \le 3n^2)). Then, output (m) lines in the following format: (x_{i,1}\;y_{i,1}\;x_{i,2}\;y_{i,2}\;x_{i,3}\;y_{i,3}): The vertices of the (i)-th triangle are ((x_{i,1},y_{i,1})), ((x_{i,2},y_{i,2})), ((x_{i,3},y_{i,3})). You may output the vertices of one triangle in any order (clockwise or counterclockwise). Your output will be accepted if it satisfies all conditions and the maximum size given is correct. In the first test case, the example output has (2) triangles as shown in the following image: In the second test case, the example output has (12) triangles as shown in the image on the left: As the triangles are not required to be right triangles, the set of triangles shown in the image on the right will also be considered valid.

Tutorials

Codeforces Round 1080 (Div. 3) Editorial

Submissions

Submission Id
Author(s)
Index
Submitted
Verdict
Language
Test Set
Tests Passed
Time taken (ms)
Memory Consumed (bytes)
Tags
Rating
363186130 Teymur1 H Feb. 15, 2026, 5:03 p.m. OK C++17 (GCC 7-32) TESTS 12 62 819200
363186178 Dimozavr H Feb. 15, 2026, 5:03 p.m. OK C++17 (GCC 7-32) TESTS 12 62 921600
363229002 Darko2026 H Feb. 16, 2026, 3 a.m. OK C++17 (GCC 7-32) TESTS 12 78 102400
363193982 cscsksks H Feb. 15, 2026, 5:30 p.m. OK C++17 (GCC 7-32) TESTS 12 78 102400
363221718 pandaa73 H Feb. 15, 2026, 11:09 p.m. OK C++17 (GCC 7-32) TESTS 12 78 819200
363201458 BABEL H Feb. 15, 2026, 6:23 p.m. OK C++17 (GCC 7-32) TESTS 12 78 16076800
363224739 pupil256 H Feb. 16, 2026, 12:56 a.m. OK C++17 (GCC 7-32) TESTS 12 93 0
363203289 dirtblock H Feb. 15, 2026, 6:39 p.m. OK C++17 (GCC 7-32) TESTS 12 93 0
363195164 _criminal H Feb. 15, 2026, 5:38 p.m. OK C++17 (GCC 7-32) TESTS 12 93 819200
363192837 mikistarlm H Feb. 15, 2026, 5:23 p.m. OK C++17 (GCC 7-32) TESTS 12 109 102400
363190697 AlRntn H Feb. 15, 2026, 5:13 p.m. OK C++20 (GCC 13-64) TESTS 12 46 0
363197324 a_foolish_OIer H Feb. 15, 2026, 5:52 p.m. OK C++20 (GCC 13-64) TESTS 12 46 1024000
363190410 amod_24 H Feb. 15, 2026, 5:13 p.m. OK C++20 (GCC 13-64) TESTS 12 46 7168000
363225083 EricZzzzz H Feb. 16, 2026, 1:07 a.m. OK C++20 (GCC 13-64) TESTS 12 62 0
363195157 khoianh H Feb. 15, 2026, 5:38 p.m. OK C++20 (GCC 13-64) TESTS 12 62 0
363186604 OG_Matveychick1 H Feb. 15, 2026, 5:04 p.m. OK C++20 (GCC 13-64) TESTS 12 62 0
363234136 UKE2006 H Feb. 16, 2026, 4:40 a.m. OK C++20 (GCC 13-64) TESTS 12 62 102400
363189321 MagnusCarlsen321 H Feb. 15, 2026, 5:10 p.m. OK C++20 (GCC 13-64) TESTS 12 62 102400
363193737 Owstin H Feb. 15, 2026, 5:29 p.m. OK C++20 (GCC 13-64) TESTS 12 62 307200
363184096 LOV34EVER H Feb. 15, 2026, 4:58 p.m. OK C++20 (GCC 13-64) TESTS 12 62 2457600
363226162 lam09062016 H Feb. 16, 2026, 1:44 a.m. OK C++23 (GCC 14-64, msys2) TESTS 12 46 0
363205435 AllFiction H Feb. 15, 2026, 7 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 46 0
363190368 makeit420 H Feb. 15, 2026, 5:13 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 46 2457600
363224998 Ladamalina H Feb. 16, 2026, 1:04 a.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363223592 Gokuu007 H Feb. 16, 2026, 12:21 a.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363209456 YuukiS H Feb. 15, 2026, 7:46 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363200815 Modest_Xi H Feb. 15, 2026, 6:18 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363200242 El_gge H Feb. 15, 2026, 6:14 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363198732 Anemone_ H Feb. 15, 2026, 6:02 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363197615 avner.m.lim H Feb. 15, 2026, 5:54 p.m. OK C++23 (GCC 14-64, msys2) TESTS 12 62 0
363196677 rachit.gupta H Feb. 15, 2026, 5:48 p.m. OK Java 21 TESTS 12 234 409600
363196629 shubhansh_gupta H Feb. 15, 2026, 5:47 p.m. OK Java 21 TESTS 12 234 409600
363191683 akane646 H Feb. 15, 2026, 5:17 p.m. OK PyPy 3-64 TESTS 12 125 25600000
363205181 Ergodic137 H Feb. 15, 2026, 6:57 p.m. OK PyPy 3-64 TESTS 12 140 13209600
363235629 gameon030609 H Feb. 16, 2026, 5:01 a.m. OK PyPy 3-64 TESTS 12 156 9625600
363184688 UcUkoyo H Feb. 15, 2026, 4:59 p.m. OK PyPy 3-64 TESTS 12 171 19353600
363188714 akane646 H Feb. 15, 2026, 5:09 p.m. OK PyPy 3-64 TESTS 12 171 25804800
363229873 Meguhine H Feb. 16, 2026, 3:21 a.m. OK PyPy 3-64 TESTS 12 187 19251200
363195875 sigtuna H Feb. 15, 2026, 5:43 p.m. OK PyPy 3-64 TESTS 12 203 10240000
363198576 Juk-Skorobei H Feb. 15, 2026, 6:01 p.m. OK PyPy 3-64 TESTS 12 203 19353600
363198122 Only365 H Feb. 15, 2026, 5:58 p.m. OK PyPy 3-64 TESTS 12 203 19353600
363240177 Msgnh H Feb. 16, 2026, 6:05 a.m. OK PyPy 3-64 TESTS 12 218 10240000
363202309 patacca H Feb. 15, 2026, 6:30 p.m. OK Rust 2024 TESTS 12 78 3072000

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