STL deque accessing by index is O(1)?

Question

I\'ve read that accessing elements by position index can be done in constant time in a STL deque. As far as I know, elements in a deque may be stored in several non-contiguo

Answer 1

I found this deque implementation from Wikipedia:

Storing contents in multiple smaller arrays, allocating additional arrays at the beginning or end as needed. Indexing is implemented by keeping a dynamic array containing pointers to each of the smaller arrays.

I guess it answers my question.