Priority Queue

A priority queue assigns a priority value to each element in the queue. Elements are dequeued based on their priority, with higher-priority elements being processed first. Priority queues are used in scenarios where the order of processing depends on priorities.

Operations

Queue Operations

Enqueue
Adding an element to the back (also known as the rear or tail) of the queue.

Dequeue
Removing and returning the element from the front (also known as the head) of the queue.

Peek
Viewing the element at the front of the queue without removing it.

Demonstration

Priority Queue Interactive Demonstration

Code

Priority Queue Python Code

import heapq

class PriorityQueue:
    def __init__(self):
        self.elements = []

    def is_empty(self):
        return len(self.elements) == 0

    def enqueue(self, item, priority):
        heapq.heappush(self.elements, (priority, item))

    def dequeue(self):
        if not self.is_empty():
            return heapq.heappop(self.elements)[1]
        else:
            print("Queue is empty")

# Example usage:
if __name__ == "__main__":
    pq = PriorityQueue()
    pq.enqueue("Task 1", 3)
    pq.enqueue("Task 2", 1)
    pq.enqueue("Task 3", 2)

    print("Dequeue:", pq.dequeue())  # Dequeue Task 2 with the highest priority
    print("Is empty?", pq.is_empty())  # False
    print("Dequeue:", pq.dequeue())  # Dequeue Task 3 with the next highest priority
    print("Dequeue:", pq.dequeue())  # Dequeue Task 1 with the lowest priority
    print("Is empty?", pq.is_empty())  # True

Resources

Google Slides