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Queue using Array

Certification: Basic Level Accuracy: 100% Submissions: 7 Points: 8

Write a Java program to implement a queue using an array. The queue should support enqueue, dequeue, peek, isEmpty, and isFull operations.

Example 1
    

  • Input:
    enqueue(10)
    enqueue(20)
    enqueue(30)
    dequeue()
    peek()
    • 

  • Output:
    10 dequeued from the queue
    Front element is: 20
    • 

  • Explanation:

      

    • Queue is FIFO. 10 dequeued, 20 is now at front
      • 

    

    •
Example 2
    

  • Input:
    enqueue(10)
    isEmpty()
    enqueue(20)
    enqueue(30)
    isFull()
    dequeue()
    dequeue()
    dequeue()
    isEmpty()
    • 

  • Output:
    Queue is not empty
    Queue is not full
    10 dequeued
    20 dequeued
    30 dequeued
    Queue is empty
    •
Constraints
    

  • Fixed capacity set during initialization
    • 

  • Time Complexity: O(1)
    • 

  • Space Complexity: O(n)
    • 

  • Must handle overflow and underflow
    •
ArraysQueueTutorialspointTCS (Tata Consultancy Services)
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Hint
Solution

Solution Hints

    
  
  • Use a circular array to efficiently utilize space.
    • 
  
  • Keep track of both front and rear indices.
    • 
  
  • For enqueue, increment rear and add the element.
    • 
  
  • For dequeue, remove the front element and increment front.
    • 
  
  • Use modulo arithmetic to handle wraparound in the circular array.
    •

Steps to solve by this approach:

 Step 1: Create a class with an array, variables to track front and rear indices, size, and capacity.

 Step 2: Initialize front and size to 0, and rear to capacity-1 in the constructor.

 Step 3: Implement the enqueue method by updating rear using modulo arithmetic and adding the element.

 Step 4: Implement the dequeue method by returning the element at front and updating front using modulo arithmetic.

 Step 5: Implement the peek method to return the element at front without modifying any indices.

 Step 6: Implement isEmpty method to check if size is 0.

 Step 7: Implement isFull method to check if size equals capacity.

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