Codeforces Round 1124 (Div. 1)

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ContestId
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Phase
Frozen
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Relative Time
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2268 Codeforces Round 1124 (Div. 1) FINISHED False 9000 746666 Sept. 26, 2026, 2:35 p.m.

Problems

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Type
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( 169 ) F Deglado PROGRAMMING constructive algorithms

You are given a (2n \times 2n) grid (a) where each column is a permutation(^{\text{∗}}) of length (2n). We want to sort all columns in ascending order from top to bottom by performing the following operation: Choose a (2 \times 2) subgrid and swap the two top elements with the two bottom elements. More formally, you can choose two integers (i) and (j) ((1 \leq i, j \lt 2n)), then swap (a_{i,j}) with (a_{i+1,j}) and swap (a_{i,j+1}) with (a_{i+1,j+1}). More formally, you can choose two integers (i) and (j) ((1 \leq i, j \lt 2n)), then swap (a_{i,j}) with (a_{i+1,j}) and swap (a_{i,j+1}) with (a_{i+1,j+1}). You have to sort all columns using at most (n \cdot \binom{2n}{2} + 9n) operations, or determine that it is impossible. Note that you do not need to minimize the number of operations. (^{\text{∗}})A permutation of length (m) is an array consisting of (m) distinct integers from (1) to (m) in arbitrary order. For example, (2,3,1,5,4) is a permutation, but (1,2,2) is not a permutation ((2) appears twice in the array), and (1,3,4) is also not a permutation ((m=3) but there is (4) in the array). Each test contains multiple test cases. The first line contains the number of test cases (t) ((1 \le t \le 500)). The description of the test cases follows. The first line of each test contains a single integer (n) ((1 \leq n \leq 80)). The (i)-th line of the next (2n) lines contains (2n) integers (a_{i,1},a_{i,2},\ldots,a_{i,2n}) ((1 \leq a_{i,j} \leq 2n)) — the elements of the (i)-th row of the grid. It is guaranteed that every column in the grid forms a permutation of length (2n). It is guaranteed that the sum of (n^3) over all test cases does not exceed (80^3). For each test case, if it is impossible to sort all columns in at most (n \cdot \binom{2n}{2} + 9n) operations, print $$$-1

Tutorials

157140

Submissions

Submission Id
Author(s)
Index
Submitted
Verdict
Language
Test Set
Tests Passed
Time taken (ms)
Memory Consumed (bytes)
Tags
Rating
392258807 rnzhemvhtm F Sept. 26, 2026, 10:52 p.m. OK C++17 (GCC 7-32) TESTS 170 93 0
392240267 David-M F Sept. 26, 2026, 5:53 p.m. OK C++17 (GCC 7-32) TESTS 169 1234 13312000
392260036 Ormlis F Sept. 26, 2026, 11:39 p.m. OK C++20 (GCC 13-64) TESTS 170 156 10035200
392239690 123456789010111213141516 F Sept. 26, 2026, 5:48 p.m. OK C++20 (GCC 13-64) TESTS 169 171 9420800
392231833 Ormlis F Sept. 26, 2026, 4:55 p.m. OK C++20 (GCC 13-64) TESTS 169 171 10035200
392235881 17326020824 F Sept. 26, 2026, 5:19 p.m. OK C++20 (GCC 13-64) TESTS 169 187 10035200
392244867 AlefHeKaaf F Sept. 26, 2026, 6:35 p.m. OK C++20 (GCC 13-64) TESTS 170 187 22118400
392282363 macepag726 F Sept. 27, 2026, 4:46 a.m. OK C++23 (GCC 14-64, msys2) TESTS 170 156 10137600
392281442 mhb2010 F Sept. 27, 2026, 4:28 a.m. OK C++23 (GCC 14-64, msys2) TESTS 170 156 10137600
392262408 azizs F Sept. 27, 2026, 1:06 a.m. OK C++23 (GCC 14-64, msys2) TESTS 170 171 10137600
392286606 xxxzenu F Sept. 27, 2026, 5:43 a.m. OK C++23 (GCC 14-64, msys2) TESTS 170 187 10035200
392233530 idontwannadothisanymore F Sept. 26, 2026, 5:02 p.m. OK C++23 (GCC 14-64, msys2) TESTS 169 187 10240000
392278035 ShangshangZhang F Sept. 27, 2026, 3:22 a.m. OK C++23 (GCC 14-64, msys2) TESTS 170 187 22937600
392253620 RecurseKing F Sept. 26, 2026, 8:36 p.m. OK C++23 (GCC 14-64, msys2) TESTS 170 1500 10547200
392253950 XXJACK F Sept. 26, 2026, 8:42 p.m. OK Java 21 TESTS 170 625 63488000
392286734 xxxzenu F Sept. 27, 2026, 5:44 a.m. OK PyPy 3-64 TESTS 170 500 30822400

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