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text
In order to support fast random access, the elements in the vector are stored continuously (contiguous memory space)
As mentioned earlier, adding elements to the vector may cause the reallocation of the entire container memory space
In order to reduce the number of re-allocations of container space, every time a new memory space has to be acquired, a larger memory space (2 times?) than the actual demand is allocated.
This strategy ensures that the expansion operation of vector is usually faster than list and deque
Management container
c.shrink_to_fit()
c.capacity()
c.reserve( n )
capacity How many elements can be saved without reallocating the memory space. Reserve allocates memory space that can hold
at least n elements.
shrink_to_fit() Request to reduce capacity to the same size as size, but the request may be ignored, depending on the specific implementation
reserve(n), if n is less than the actual capacity, do nothing, reserve will not reduce the memory space occupied by the
container. resize only changes the number of elements in the container, not the capacity of the container
shrink_to_fit only applies to vector, string and deque
capacity and reserve only apply to vector and string