Is the checker occasionally failing to detect that a test has completed, and so giving a TLE?↵
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In [Codeforces round 727 problem C](https://codeforces.net/contest/1539/problem/C), when the system tests were run, I got TLE on my [submission](https://codeforces.net/contest/1539/submission/120080619) on test 18. Looking at the results my code printed the result before getting the TLE, and my code should exit immediately after printing the result. At first I assumed that I was just unlucky, and my code had taken precisely one second to run, so had been stopped just before exiting.↵
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After the contest I tried modifying my code in various ways to speed it up, for example ↵
https://codeforces.net/contest/1539/submission/120193428 and https://codeforces.net/contest/1539/submission/120195587.↵
In all cases I got exactly the same result; my code printed an answer but still got a TLE. It seems extremely unlikely that every single version of my code would take precisely 1 second to run.↵
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To confirm this, I tried running my most recent version under Python3 instead of PyPy3. This is normally slower, but on this occasion passed all tests without any TLEs. See https://codeforces.net/contest/1539/submission/120195637↵
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In [Codeforces round 727 problem C](https://codeforces.net/contest/1539/problem/C), when the system tests were run, I got TLE on my [submission](https://codeforces.net/contest/1539/submission/120080619) on test 18. Looking at the results my code printed the result before getting the TLE, and my code should exit immediately after printing the result. At first I assumed that I was just unlucky, and my code had taken precisely one second to run, so had been stopped just before exiting.↵
↵
After the contest I tried modifying my code in various ways to speed it up, for example ↵
https://codeforces.net/contest/1539/submission/120193428 and https://codeforces.net/contest/1539/submission/120195587.↵
In all cases I got exactly the same result; my code printed an answer but still got a TLE. It seems extremely unlikely that every single version of my code would take precisely 1 second to run.↵
↵
To confirm this, I tried running my most recent version under Python3 instead of PyPy3. This is normally slower, but on this occasion passed all tests without any TLEs. See https://codeforces.net/contest/1539/submission/120195637↵