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?

  • Vote: I like it
  • 0
  • Vote: I do not like it

Comments Comments (2)
| Write comment?
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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

→ Reply
»
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://codeforces.net/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.

→ Reply