A priority queue operates as a type of queue where each item is assigned a specific priority level. Items are processed based on their priority, ensuring that higher priority items are handled first. In cases where items share the same priority, they are processed in the order they were added to the queue. Various data structures like arrays, linked lists, heap data structures, and binary search trees can be employed to construct a priority queue. Notably, the heap data structure is particularly efficient in implementing priority queues compared to other data structures.
By using array and wrap around, we implement Queues:
An array has the ability to implement a queue:
- It takes O(1) time to add and remove items.
- size is restricted
- must keep track of where the queue starts and stops in the field
- The queue may eventually "wrap around" the end of the field; this is not an issue, but rather a special circumstance that must be handled.
What exactly is Wrap Around?
To address the issue of being unable to enqueue an element when the queue is not full, the queue wraps around to the beginning of the array using both front and back pointers. This circular behavior is commonly referred to as a ring queue or ring buffer. Once wrapped, the back pointer shifts below the front pointer, effectively reversing their initial positions.
Why can't a priority queue be like a regular queue and wrap around?
- One of most popular priority queue implementation is a binary heap, that doesn't advantage from wrapping.
- We could implement a priority queue in such a ring buffer, however efficiency may decrease.
- It really is vital to understand that such a priority queue is a data structure that is abstract. It specifies the operations and not their execution. A priority queue can be implemented in various ways, including a binary heap, sorted array, unsorted array, binary tree, skipped list, linked list, and others.
- A priority queue might be built in a variety of ways.
- In contrast, a binary heap seems to be a subset of the priority queue abstract data type.
- Through perspective of stack vs. queue, stacks and queues are simply specializations of priority queues.
- Once time is factored in, the queue (a FIFO data structure) becomes a priority queue, with the oldest item receiving the highest priority.
- A stack (LIFO data structure) is a prioritized queue that favours the most recently added item.
Conclusion:
A queue represents a sequential arrangement of elements, adhering to a particular sequence. It retrieves elements based on the FIFO (First In First Out) approach. Queues find extensive application in scenarios like multithreading and priority queuing to oversee thread management efficiently. Within programming, the queue stands as a fundamental data structure. It functions on the principle of FIFO (First In First Out) and remains accessible from both terminations. Insertion of data occurs at the rear end or tail, while deletion happens at the front end or head of the queue.