Applications of Priority Queue

Aditya Narayan Joardar
Last Updated: May 13, 2022

Introduction

This article is based on the various day-to-day applications of Priority Queue. One may ask, what is a Priority Queue? Priority queues are similar to Queue, but the elements do not come out in FIFO (First In First Out) order; instead, they come out based on their “priority.”
 

Imagine a scenario where ten people need to exit a room. The people are numbered according to their time of entry as P1, P2, P3 …. P10. This means that P1 entered first and P10 entered last. If it were a normal queue exit, then P1 would have exited first, then P2, then P3, and so on.

But now, there is a catch. All the people present in the room have different “status” or “priorities.” For example, P1 has priority 3, P5 has priority 1. This means that P5 is of higher importance than P1 and will exit the room first (provided the priorities are assigned in increasing order and lower values have more priority). 
 

A priority is a value that marks the “importance” of a queue element. In a priority queue, the order of entry is not of much concern; the order of exit is. Each element of the priority queue is enqueued based on their priority. The priority can be of two types depending on the situation-

  • Lower value higher priority
  • Higher value higher priority

 

If you have any doubts regarding priority queues, head over to our CN Library and read about  Priority Queue.


So without any further ado, let’s head to the applications of Priority Queue.

Applications of Priority Queue

  1. In Dijkstra’s algorithm: We all know that if we want to find the minimum cost path from a source vertex to a destination vertex, we use Dijkstra’s Algorithm. In the efficient approach of Dijkstra’s Algorithm, we store the graph in an adjacency list. We then use a priority queue to extract the minimum path. To know more about this approach, go to Dijkstra's Algorithm.
     
  2. In Prim’s Algorithm: In the case of Prim’s Algorithm, we use a priority queue to store keys of nodes and extract minimum key nodes at every step.
     
  3. In Artificial Intelligence: A priority queue is used while implementing the A* search algorithm. A* algorithm is used to approximate the shortest path in real-life scenarios.
     
  4. In data compression: We use a priority queue in Huffman Encoding to implement the min-heap. Huffman Encoding is one of the famous data compression techniques used in compression formats like PKZIP, GZIP. 
     
  5. In Operating Systems: In the load balancing algorithms, we use priority queues to maintain the flow of operations. Good load-balancing algorithms ensure a smoother flow and optimize the response time in various computations.

Frequently Asked Questions

  1. What is a Priority Queue?
    A queue where the elements have some “importance” or “priority” is called a priority queue. To know more about heaps and priority queues in-depth visit, Heap and Priority Queue.
     
  2. How can we implement a Priority Queue?
    A priority queue can be implemented using a linked list. To know more about the same visit, Priority Queue Implementation.

Key Takeaways

In a nutshell, we discussed the various applications of Priority Queue. We first discussed a summary of Priority Queues and summed up our discussion with the different applications and some FAQs.

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