Does this sound familiar? But we'll look into it more.
They are a group of items. The variation is between where to insert an item and which item to remove. Stacks operate on a last-in-first-out (LIFO) basis, whereas queues operate on a first-in-first-out (FIFO) basis.
Stacks
A stack's main
operations are push, pop, and is Empty.
We use the terms
push to insert an item on top of the stack and pop to remove the most recently
inserted one.
(Source)
-Pop
Pop not only
removes but also returns the most recently inserted item.
(Source)
Consideration
Of Stack With Array Implementation
●
Overflow: occurs when a user attempts to
insert an item into a full-stack. So, either issue an exception or employ array
resizing.
●
Underflow: If a user attempts to delete from
an empty stack, an exception is thrown.
●
Null Items: Do we allow for the insertion of
null items? Yes, we do in some circumstances.
●
Loitering: is the act of retaining a reference
to an object when it is no longer required. When we remove an item from the
stack, we simply decrement N without assigning the item to null.
Stack
Analysis - Linked List Vs Arrays
Time - Linked List
techniques consume constant time, however, they are nonetheless inefficient
owing to object definition and dealing with links. Accessing arrays is
substantially faster; it takes O (1).
Memory - Because of
the size of node objects, linked lists demand extra memory (see figure below).
Arrays, on the other hand, demand less memory space.
(Source)
Stack Applications
●
The web browser's back button
●
Compiler
●
Dijkstra’s two-stack algorithm
●
…and the list continues on and on.
Queues
A queue's basic
operations are enqueue, dequeue, and is Empty.
-Enqueue
(Source)
If the queue was
empty before inserting an item, "first" should correspond to the
newly generated node as well, and so "oldlast" will be null.
-Dequeue
Dequeue not only
removes the initial item added but also returns it.
If the queue is
empty after removing an item, "last" should be null as well.
(Source)
Consideration
Of Queues With Array Implementation
It's the same
consideration that was raised with Stack.
●
Underflow & Overflow: We didn't think
about what happens when we put an item into a full queue or delete an item from
an empty queue.
●
Null Items: we allow the user to enter null
values.
● Loitering: We did not remove references to items that were no longer required.
Queue
Analysis — Linked List Vs Arrays
●
Time is the same as it is with
Stack when utilizing Linked Lists and Arrays.
●
Memory works in the same way as
Stack, but with Linked Lists and Arrays. It just necessitates more memory for
the two points.
Conclusion
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