Hello 2026

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ContestId
Name
Phase
Frozen
Duration (Seconds)
Relative Time
Start Time
2183 Hello 2026 FINISHED False 10800 8609123 Jan. 7, 2026, 2:35 p.m.

Problems

Solved
Index
Name
Type
Tags
Community Tag
Rating
( 218 ) G Snake Instructions PROGRAMMING interactive

This is an interactive problem. There are (n) snakes on the number line. The (i)-th snake is located at the position (a_i) and has a speed (s_i). You know the position of each snake, and that the speed of each snake is an integer from (0) to (2) inclusive, but you do not know the exact speed of each snake. It is guaranteed that no two snakes are at the same position. To figure out the snakes' speed, you may give up to (3) instructions. Each instruction should be given in the form of a binary string of length (m) containing letters L and R ((1 \leq m \leq 4n)). After receiving this instruction, the snakes will move for (m) seconds. On the (i)-th second, if (s_i=) L , then all snakes move left for that second. Otherwise, all snakes move right for that second. If two snakes are at the same location at any given point (including if the time is not an integer number of seconds), the faster snake is removed from the board. After all (m) seconds have passed, you are given the number of remaining snakes, as well as the location of all remaining snakes. Note that each instruction is independent of each other – that means that all snakes are revived and moved to their original positions. Your task is to find the speed of all snakes. However, it may be the case that it is impossible to find the speed of at least one snake. If this is the case, you must report -1 instead. You should only output -1 if it is impossible to figure out the speed of at least one snake, no matter which instructions are given. If you report -1 when there are a series of at most (3) instructions that will uniquely determine the speed of each snake, you will get the Wrong Answer verdict. Similarly, you will receive the Wrong Answer verdict if you did not report -1 when the configuration is impossible to determine, even if you correctly guessed the speeds. Each test contains multiple test cases. The first line contains the number of test ca

Tutorials

Submissions

Submission Id
Author(s)
Index
Submitted
Verdict
Language
Test Set
Tests Passed
Time taken (ms)
Memory Consumed (bytes)
Tags
Rating
356854826 jdurie G Jan. 7, 2026, 5:01 p.m. OK C++17 (GCC 7-32) TESTS 140 187 8396800
356862754 ArturSmolenski G Jan. 7, 2026, 5:25 p.m. OK C++17 (GCC 7-32) TESTS 140 531 16179200
356853920 hos.lyric G Jan. 7, 2026, 4:59 p.m. OK C++17 (GCC 7-32) TESTS 140 765 105369600
356889334 ljw01 G Jan. 8, 2026, 12:47 a.m. OK C++20 (GCC 13-64) TESTS 140 125 8089600
356896942 Survivor_winner G Jan. 8, 2026, 3:34 a.m. OK C++20 (GCC 13-64) TESTS 140 140 5017600
356900577 installb G Jan. 8, 2026, 4:29 a.m. OK C++20 (GCC 13-64) TESTS 140 187 29388800
356875991 Michal_1 G Jan. 7, 2026, 7:32 p.m. OK C++20 (GCC 13-64) TESTS 140 218 7372800
356892850 adam01 G Jan. 8, 2026, 2:23 a.m. OK C++20 (GCC 13-64) TESTS 140 218 18432000
356900946 installb G Jan. 8, 2026, 4:34 a.m. OK C++20 (GCC 13-64) TESTS 140 234 29388800
356861593 strapple G Jan. 7, 2026, 5:21 p.m. OK C++20 (GCC 13-64) TESTS 140 312 6451200
356850832 MYFJCHX G Jan. 7, 2026, 4:50 p.m. OK C++20 (GCC 13-64) TESTS 140 359 3276800
356892335 Nightmare07 G Jan. 8, 2026, 2:12 a.m. OK C++20 (GCC 13-64) TESTS 140 375 18534400
356858996 20333333333 G Jan. 7, 2026, 5:13 p.m. OK C++20 (GCC 13-64) TESTS 140 390 10137600
356888474 scorpion G Jan. 8, 2026, 12:15 a.m. OK C++23 (GCC 14-64, msys2) TESTS 140 125 102400
356874636 lnsuyn G Jan. 7, 2026, 7:18 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 125 102400
356853101 BurnedChicken G Jan. 7, 2026, 4:56 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 125 102400
356904920 khushicodes03 G Jan. 8, 2026, 5:26 a.m. OK C++23 (GCC 14-64, msys2) TESTS 140 140 102400
356890540 Legend_of_Bangladesh G Jan. 8, 2026, 1:29 a.m. OK C++23 (GCC 14-64, msys2) TESTS 140 140 102400
356864705 maroonrk G Jan. 7, 2026, 5:30 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 140 102400
356864540 ecnerwala G Jan. 7, 2026, 5:30 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 140 102400
356866294 katyaporay G Jan. 7, 2026, 5:34 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 156 1536000
356882669 ksun48 G Jan. 7, 2026, 9:13 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 171 16281600
356860200 Miku_Teto G Jan. 7, 2026, 5:17 p.m. OK C++23 (GCC 14-64, msys2) TESTS 140 187 6656000

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