Why would I prefer using vector to deque

Question

Since

1. they are both contiguous memory containers;
2. feature wise, deque has almost everything vector has but more, since it is more efficient to insert

Answer 1

On the one hand, vector is quite frequently just plain faster than deque. If you don't actually need all of the features of deque, use a vector.

On the other hand, sometimes you do need features which vector does not give you, in which case you must use a deque. For example, I challenge anyone to attempt to rewrite this code, without using a deque, and without enormously altering the algorithm.