I use Microsoft Visual Studio as my IDE, so I submit my solutions here using the Visual C++ 2017 compiler. Recently, I submitted a solution to 1180D - Толик и дядя which passed the pretests but TLEed on a system test. My solution (55894505) is a bit overcomplicated, but it runs in O(nm) which should be fast enough. In fact, it passes in 280ms when submitted using G++. A custom test shows that my solution takes 1029ms for the system test case which it TLEed on, and adding
cin.tie(nullptr) only decreased the time by 20ms, still over the time limit. I was only able to get AC with MSVC++ by using
printf instead of
cout. So for this solution, MSVC++ is apparently three to four times slower than G++.
I then did a custom test with MSVC++ 2010 instead of MSVC++ 2017, and I got 904ms without fast I/O and 842ms with fast I/O, which doesn't seem to make any sense. I got similar results with the official solution, so my code isn't the problem. According to https://codeforces.com/blog/entry/4088, the command line for MSVC++ 2010 includes the
/O2 flag which should optimize for maximum speed, while the command line for MSVC++ 2017 isn't shown. Why is MSVC++ so much slower than G++ here, and why is MSVC++ 2017 slower than MSVC++ 2010?