Strange situation(three different results with different compilers)

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Hello, Codeforces.

I've sent three submissions with different compilers on problem 1553E - Permutation Shift from last round and got different results(OK, ML 1, WA 1)

123344376

123363613

123363479

Then i've ran valgrind (g++ 11.1.0) and discovered strange "still reachable" memory addresses, somehow connected with ios_base::sync_with_stdio. Then I realised, that fast IO was in solve function, which is called in main $$$T$$$ times for each test case. Then I moved it to main and got OK in all compilers.

valgrind output on sample

==36581== 
==36581== HEAP SUMMARY:
==36581==     in use at exit: 122,880 bytes in 6 blocks
==36581==   total heap usage: 120 allocs, 114 frees, 197,964 bytes allocated
==36581== 
==36581== 8,192 bytes in 1 blocks are still reachable in loss record 1 of 6
==36581==    at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579)
==36581==    by 0x4982194: _M_allocate_internal_buffer (fstream.tcc:56)
==36581==    by 0x4982194: std::basic_filebuf<char, std::char_traits<char> >::_M_allocate_internal_buffer() (fstream.tcc:49)
==36581==    by 0x497FEBA: __gnu_cxx::stdio_filebuf<char, std::char_traits<char> >::stdio_filebuf(_IO_FILE*, std::_Ios_Openmode, unsigned long) (stdio_filebuf.h:161)
==36581==    by 0x492E6A2: std::ios_base::sync_with_stdio(bool) (ios_init.cc:181)
==36581==    by 0x109410: solve() (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581==    by 0x109AB8: main (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581== 
==36581== 8,192 bytes in 1 blocks are still reachable in loss record 2 of 6
==36581==    at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579)
==36581==    by 0x4982194: _M_allocate_internal_buffer (fstream.tcc:56)
==36581==    by 0x4982194: std::basic_filebuf<char, std::char_traits<char> >::_M_allocate_internal_buffer() (fstream.tcc:49)
==36581==    by 0x497FEBA: __gnu_cxx::stdio_filebuf<char, std::char_traits<char> >::stdio_filebuf(_IO_FILE*, std::_Ios_Openmode, unsigned long) (stdio_filebuf.h:161)
==36581==    by 0x492E6C6: std::ios_base::sync_with_stdio(bool) (ios_init.cc:182)
==36581==    by 0x109410: solve() (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581==    by 0x109AB8: main (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581== 
==36581== 8,192 bytes in 1 blocks are still reachable in loss record 3 of 6
==36581==    at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579)
==36581==    by 0x4982194: _M_allocate_internal_buffer (fstream.tcc:56)
==36581==    by 0x4982194: std::basic_filebuf<char, std::char_traits<char> >::_M_allocate_internal_buffer() (fstream.tcc:49)
==36581==    by 0x497FEBA: __gnu_cxx::stdio_filebuf<char, std::char_traits<char> >::stdio_filebuf(_IO_FILE*, std::_Ios_Openmode, unsigned long) (stdio_filebuf.h:161)
==36581==    by 0x492E6EA: std::ios_base::sync_with_stdio(bool) (ios_init.cc:183)
==36581==    by 0x109410: solve() (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581==    by 0x109AB8: main (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581== 
==36581== 32,768 bytes in 1 blocks are still reachable in loss record 4 of 6
==36581==    at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579)
==36581==    by 0x4983F47: _M_allocate_internal_buffer (fstream.tcc:56)
==36581==    by 0x4983F47: std::basic_filebuf<wchar_t, std::char_traits<wchar_t> >::_M_allocate_internal_buffer() (fstream.tcc:49)
==36581==    by 0x49800BA: __gnu_cxx::stdio_filebuf<wchar_t, std::char_traits<wchar_t> >::stdio_filebuf(_IO_FILE*, std::_Ios_Openmode, unsigned long) (stdio_filebuf.h:161)
==36581==    by 0x492E757: std::ios_base::sync_with_stdio(bool) (ios_init.cc:190)
==36581==    by 0x109410: solve() (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581==    by 0x109AB8: main (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581== 
==36581== 32,768 bytes in 1 blocks are still reachable in loss record 5 of 6
==36581==    at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579)
==36581==    by 0x4983F47: _M_allocate_internal_buffer (fstream.tcc:56)
==36581==    by 0x4983F47: std::basic_filebuf<wchar_t, std::char_traits<wchar_t> >::_M_allocate_internal_buffer() (fstream.tcc:49)
==36581==    by 0x49800BA: __gnu_cxx::stdio_filebuf<wchar_t, std::char_traits<wchar_t> >::stdio_filebuf(_IO_FILE*, std::_Ios_Openmode, unsigned long) (stdio_filebuf.h:161)
==36581==    by 0x492E77B: std::ios_base::sync_with_stdio(bool) (ios_init.cc:191)
==36581==    by 0x109410: solve() (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581==    by 0x109AB8: main (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581== 
==36581== 32,768 bytes in 1 blocks are still reachable in loss record 6 of 6
==36581==    at 0x484021F: operator new[](unsigned long) (vg_replace_malloc.c:579)
==36581==    by 0x4983F47: _M_allocate_internal_buffer (fstream.tcc:56)
==36581==    by 0x4983F47: std::basic_filebuf<wchar_t, std::char_traits<wchar_t> >::_M_allocate_internal_buffer() (fstream.tcc:49)
==36581==    by 0x49800BA: __gnu_cxx::stdio_filebuf<wchar_t, std::char_traits<wchar_t> >::stdio_filebuf(_IO_FILE*, std::_Ios_Openmode, unsigned long) (stdio_filebuf.h:161)
==36581==    by 0x492E79F: std::ios_base::sync_with_stdio(bool) (ios_init.cc:192)
==36581==    by 0x109410: solve() (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581==    by 0x109AB8: main (in /home/thematdev/AlgoProgs/tinkoffgeneration2020/tmp/HarbourSpaceScholarship/problemE/a.out)
==36581== 
==36581== LEAK SUMMARY:
==36581==    definitely lost: 0 bytes in 0 blocks
==36581==    indirectly lost: 0 bytes in 0 blocks
==36581==      possibly lost: 0 bytes in 0 blocks
==36581==    still reachable: 122,880 bytes in 6 blocks
==36581==         suppressed: 0 bytes in 0 blocks
==36581== 
==36581== For lists of detected and suppressed errors, rerun with: -s
==36581== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Pretty strange and interesting situation, so I am asking those, who know what's the problem to write about it in comments. Also I am glad to see critics of my code, especially if it will help to avoid situations like this.

Rev.	By	When	Δ	Comment
en4	thematdev	2021-07-22 23:42:15	0	(published)
ru4	thematdev	2021-07-22 23:41:54	0	(опубликовано)
ru3	thematdev	2021-07-22 23:41:32	129
en3	thematdev	2021-07-22 23:40:01	86	Tiny change: 'he problem, write abo' -> 'he problem to write abo'
en2	thematdev	2021-07-22 23:30:10	55
en1	thematdev	2021-07-22 23:28:27	6876	Initial revision for English translation (saved to drafts)
ru2	thematdev	2021-07-22 23:21:36	127
ru1	thematdev	2021-07-22 23:19:58	6769	Первая редакция (сохранено в черновиках)

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