deque' provide front and back specific versions of common queue operationse you may want to enqueue an item to the front of the queue rather than the back in which case you would use method with name along the lines of enqueuefront the following list identifies operations that are commonly supported by deque'senqueuefront enqueueback dequeuefront dequeueback peekfront peekback figure shows deque after the invocation of the following methods (inorder) enqueueback( enqueuefront( enqueueback( enqueuefront( dequeuefront( dequeueback(the operations have one-to-one translation in terms of behaviour with those of normal queueor priority queue in some cases the set of algorithms that add an item to the back of the deque may be named as they are with normal queuese enqueueback may simply be called enqueue an so on some frameworks also specify explicit behaviour' that data structures must adhere to this is certainly the case in net where most collections implement an interface which requires the data structure to expose standard add method in such scenario you can safely assume that the add method will simply enqueue an item to the back of the deque with respect to algorithmic run time complexities deque is the same as normal queue that is enqueueing an item to the back of the queue is ( )additionally enqueuing an item to the front of the queue is also an ( operation deque is wrapper data structure that uses either an arrayor doubly linked list using an array as the backing data structure would require the programmer to be explicit about the size of the array up frontthis would provide an obvious advantage if the programmer could deterministically state the maximum number of items the deque would contain at any one time unfortunately in most cases this doesn' holdas result the backing array will inherently incur the expense of invoking resizing algorithm which would most likely be an (noperation such an approach would also leave the library developer