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MyCircularDeque Implementation in Multiple Languages

This README provides a detailed step-by-step explanation of how a Circular Deque is implemented across different programming languages including C++, Java, JavaScript, and Python. We'll break down the logic used in each method and how the circular nature of the deque is handled. Each section below focuses on the core concepts applied in the implementation.

C++ Implementation

Key Concepts

  1. Vector Representation:

    • The deque is implemented using a vector (deque) to store elements. An extra space (k + 1) is allocated to differentiate between the full and empty states of the deque.

  2. Pointers for Front and Rear:

    • front and rear pointers keep track of the positions at the front and rear of the deque. Initially, both are set to 0.

  3. Circular Movement:

    • Both the front and rear pointers move in a circular manner using modulo operations (%) to wrap around when they reach the end or beginning of the deque.

Methods

Constructor

  • Initializes the deque with k + 1 size to handle the wrap-around logic. The front and rear pointers are both set to 0.

insertFront

  • Checks if the deque is full using the isFull() method.
  • Moves the front pointer backward using a circular operation and inserts the value.

insertLast

  • Checks if the deque is full.
  • Inserts the value at the rear pointer's current position and moves the rear pointer forward in a circular manner.

deleteFront

  • Checks if the deque is empty.
  • Moves the front pointer forward to remove the element at the front.

deleteLast

  • Checks if the deque is empty.
  • Moves the rear pointer backward to remove the last element.

getFront and getRear

  • Returns the front or rear element. In the case of getRear, the rear pointer points to the next position, so we subtract one and wrap it around.

isEmpty and isFull

  • isEmpty: The deque is empty when front == rear.
  • isFull: The deque is full when the next position of rear equals front.

Java Implementation

Key Concepts

  1. Array Representation:

    • The deque is represented as an array (deque[]) with an extra space (k + 1) to distinguish between full and empty states.

  2. Pointers for Front and Rear:

    • Similar to C++, the front and rear pointers track the positions at the front and rear of the deque. The pointers move in a circular manner using modulo operations.

Methods

Constructor

  • Initializes an array of size k + 1 with front and rear pointers set to 0.

insertFront

  • Checks if the deque is full.
  • Moves the front pointer backward and inserts the value at the new position.

insertLast

  • Inserts a value at the rear position and moves the rear pointer forward.

deleteFront

  • Moves the front pointer forward, effectively removing the front element.

deleteLast

  • Moves the rear pointer backward to remove the last element.

getFront and getRear

  • Retrieves the front or rear element. For the rear, the rear - 1 is used, wrapped around with modulo.

isEmpty and isFull

  • Similar to C++, the deque is empty when front == rear and full when (rear + 1) % size == front.

JavaScript Implementation

Key Concepts

  1. Array Representation:

    • An array (deque[]) is used to represent the deque with an extra space (k + 1).

  2. Circular Pointer Movement:

    • The front and rear pointers are managed using modulo operations for circular movement.

Methods

Constructor

  • Initializes the array with size k + 1 and both front and rear pointers at 0.

insertFront

  • Checks if the deque is full. Moves the front pointer backward in a circular manner and inserts the value.

insertLast

  • Inserts the value at the current rear position and moves the rear pointer forward.

deleteFront

  • Moves the front pointer forward to remove the front element.

deleteLast

  • Moves the rear pointer backward to remove the last element.

getFront and getRear

  • Retrieves the front or rear element, with circular management of the rear - 1 for getRear.

isEmpty and isFull

  • Similar logic as before, empty when front == rear and full when the next position of rear matches front.

Python Implementation

Key Concepts

  1. Array Representation:

    • A list (deque[]) of size k + 1 is used to represent the deque.

  2. Pointer Management:

    • front and rear pointers are used to track the start and end of the deque, and they move circularly using modulo operations.

Methods

Constructor

  • Initializes the deque with size k + 1 and sets front and rear pointers to 0.

insertFront

  • Moves the front pointer backward and inserts the value.

insertLast

  • Inserts a value at the current rear position and moves the rear pointer forward.

deleteFront

  • Moves the front pointer forward to remove the front element.

deleteLast

  • Moves the rear pointer backward to remove the last element.

getFront and getRear

  • Retrieves the front or rear element, adjusting the rear - 1 using modulo for getRear.

isEmpty and isFull

  • Same logic as other languages, empty when front == rear, and full when (rear + 1) % size == front.

Conclusion

The Circular Deque implementation across C++, Java, JavaScript, and Python shares the same key concepts but is expressed differently based on the syntax and data structures available in each language. By utilizing circular pointers and extra space, these implementations ensure efficient handling of the deque operations.