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A queue may be implemented as circular buffers and linked lists, or by using both the stack pointer and the base pointer. Queues provide services in computer science, transport, and operations research where various entities such as data, objects, persons, or events are stored and held to be processed later. In these contexts, the queue ...
Using a dynamic array, it is possible to implement a stack that can grow or shrink as much as needed. The size of the stack is simply the size of the dynamic array, which is a very efficient implementation of a stack since adding items to or removing items from the end of a dynamic array requires amortized O(1) time.
Double-ended queues can also be implemented as a purely functional data structure. [3]: 115 Two versions of the implementation exist. The first one, called 'real-time deque, is presented below. It allows the queue to be persistent with operations in O(1) worst-case time, but requires lazy lists with memoization. The second one, with no lazy ...
An abstract stack is a last-in-first-out structure, It is generally defined by three key operations: push, that inserts a data item onto the stack; pop, that removes a data item from it; and peek or top, that accesses a data item on top of the stack without removal.
The Stack offers methods to put a new object on the Stack (method push(E e)) and to get objects from the Stack (method pop()). A Stack returns the object according to last-in-first-out (LIFO), e.g. the object which was placed latest on the Stack is returned first. java.util.Stack is a standard implementation of a stack provided by Java.
Representation of a FIFO queue with enqueue and dequeue operations. Depending on the application, a FIFO could be implemented as a hardware shift register, or using different memory structures, typically a circular buffer or a kind of list. For information on the abstract data structure, see Queue (data structure).
Circular buffering makes a good implementation strategy for a queue that has fixed maximum size. Should a maximum size be adopted for a queue, then a circular buffer is a completely ideal implementation; all queue operations are constant time. However, expanding a circular buffer requires shifting memory, which is comparatively costly.
Linked lists are among the simplest and most common data structures. They can be used to implement several other common abstract data types, including lists, stacks, queues, associative arrays, and S-expressions, though it is not uncommon to implement those data structures directly without using a linked list as the basis.