BrainNotFound's blog

Same code gives a TLE in GNU C11, but gets accepted in C++ 17
By BrainNotFound, history, 3 years ago, In English

TLE submission (GNU C11)

AC submission

The execution time is 202ms on the C++ 17 compiler, while it's greater than 1000ms on GNU C11. I have never encountered this before. What is causing this TLE?

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3 years ago, # |
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Im pretty sure c++ compilers in general are more optimized than c compilers. I can totally see that + an older version generating a code that runs 5 times slower

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3 years ago, # |
← Rev. 2   Vote: I like it +10 Vote: I do not like it

Link to an AC submission in C with a small change in IO: https://mirror.codeforces.com/contest/1600/submission/131512345

The reason was that C-style IO is pretty slow. It's pretty well-known that C-style IO is broken in terms of speed (I believe it was fixed for g++ on codeforces but not for gcc), for instance this blog talks about it in detail. I added a line to the top of your submission that makes IO in C faster.

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