Slow scanf/printf for the new 64-bit C++ compiler?

Revision en1, by q234rty, 2020-10-08 09:42:45

So during Bubble Cup 13 - Finals [Online Mirror, unrated, Div. 1] a submission(94787679) using scanf/printf by one of my friends got TLE in the contest. After the contest I tried to add fread/fwrite for that submission and got Accepted in 405ms: 94813416. What surprised me is that the same solution can also get [Accepted in 577ms] by using cin/cout(with ios_base::sync_with_stdio(0);cin.tie(0);).

There are blogs testing cin/cout vs scanf/printf in the past, like this one.Results in that blog probably still holds for those compilers, however the same experiments on the new 64-bit msys2 G++ 9.2.0 complier seem to yield bizarre results: 94881344 using cin/cout runs in 140ms while 94881344 using scanf/printf runs in 404ms.

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en18 English q234rty 2020-10-08 10:10:12 2 Tiny change: 'oing on.\nEdit: Us' -> 'oing on.\n\nEdit: Us'
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en1 English q234rty 2020-10-08 09:42:45 836 Initial revision (saved to drafts)