Hello guys,
please take a look at this two submissions, developed on Visual Studio 2019 C++, both code are exactly same:
1- GNU 17 2- MSC++ 17
So I have two questions:
1- what is the difference between these two compilers in terms of memory, at least here.
2- why this amount of memory? I checked inside my code to see how much is taken , it is not that much shown on my submissions. for test case #13 which i get MemLimit, there is only 1 * 1000000 vector. ok, so my vector<queue< int >> is nothing but 4M byte, it should never reach to 256MB ?? I always submitted to GNU because of faster time, never had memory issue.
Could you help me to learn this part.
Thanks
Hessam
In C++, a
queue<int>is actually just adeque<int>, and its push/pop operations simply call the push/pop functions of the deque inside. You can change which container a queue contains, for examplequeue<int, list<int>>is a queue that uses a linked list inside instead of a deque.A deque in libstdc++ (GCC's C++ library) is implemented as a sequence of allocated constant-sized blocks containing its elements. A deque block in libstdc++ is 512 bytes, which means that a
queue<int>containing only one element uses at least 512 bytes. (Trivia: it is 4096 bytes if you choose clang.)Therefore, if you use GCC and create a million non-empty
queue<int>s, they will use at least 512MB of memory in total. On the other hand, MSVC's library uses a much smaller block size so a million queues fit inside the memory limit.Tip: Don't create a lot of queues. In this problem, it's possible to just use vectors. If you must use a lot of queues, you can use
queue<int, list<int>>or write your own queue class.