Queue - Data Structure

What is a Queue?

A queue is a linear data structure that follows the First In First Out (FIFO) principle. This means that the first element added to the queue will be the first one to be removed.

Queue Operations

• Enqueue: Add an element to the end of the queue.
• Dequeue: Remove and return the element from the front of the queue.
• Front: Return the element at the front of the queue without removing it.
• Is Empty: Check if the queue is empty.
• Is Full (if size limit is set): Check if the queue is full.

Python Code Example for Queue

class Queue:
    def __init__(self):
        self.queue = []

    def enqueue(self, item):
        self.queue.append(item)
        print(f"Enqueued {item} to the queue.")

    def dequeue(self):
        if not self.is_empty():
            return self.queue.pop(0)
        else:
            return "Queue is empty!"

    def front(self):
        if not self.is_empty():
            return self.queue[0]
        else:
            return "Queue is empty!"

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

    def display(self):
        print("Queue: ", self.queue)

# Example usage
my_queue = Queue()
my_queue.enqueue(10)
my_queue.enqueue(20)
my_queue.display()
print(f"Dequeued item: {my_queue.dequeue()}")
print(f"Front item: {my_queue.front()}")
my_queue.display()

            

Time and Space Complexity

• Enqueue: O(1) - constant time.
• Dequeue: O(1) - constant time.
• Front: O(1) - constant time.
• Space Complexity: O(n) - where n is the number of elements in the queue.

Visualization of Queue Operations