Last Updated: 18 January, 2025 6 Mins Read
Priority queues are a powerful data structure in computer science that provide efficient management of prioritized elements. They are widely used in many real-world applications and algorithms where prioritization is crucial for performance and correctness.
In this tutorial, we are going to explore what a priority queue is in data structure, types, basic operations, implementations, use cases in various real-world scenarios, advantages, and disadvantages.
A priority queue is one particular kind of queue where each element of a queue is associated with a priority, and elements are processed according to their priority, which means higher-priority elements are processed first.
In a priority queue, elements are processed (dequeued) according to their priority rather than their order of insertion (FIFO). Higher priority elements are dequeued first, followed by lower priority elements.
For instance, priority queues are essential in scheduling tasks in operating systems, where processes with higher importance must be executed before those with lesser priority. Additionally, they play a vital role in graph algorithms, such as Dijkstra's and Prim's, where maintaining the order of exploration based on edge weights or distances is fundamental.
Characteristics of a Priority queue:
In most cases, the element's value is taken into consideration for assigning the priority. As an illustration,
The highest priority element is the one with the highest value. In some situations, on the other hand, we can assume the element with the lowest value as the highest priority element. Setting priorities based on our requirements is also possible in the Priority Queue.
We can implement a priority queue using an array, a linked list, a heap data structure, or a binary search tree. Heap data structures are more preferred as compared to other data structures because heap data structures provide an efficient way to implement priority queues.
Given a simple example of Priority Queue in Java.
Output
Queue is full. Element removed from the Priority Queue: 15 Element at front: 25 -------------------- index : 4 3 2 1 0 -------------------- Queue: 25 35 45 55
That's all, guys. I hope this article is helpful for you.
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