Deque

A deque is a data structure that allows elements to be added or removed from both ends, making it more versatile than a traditional queue or stack. In C# there is no build-in deque but it can be impleted using LinkedList and List classes C#.

Implementing using LinkedList Class

LinkedList<T> deque = new LinkedList<T>();

• T: Specifies the element type.

Example 1

The below example shows how to implement deque using LinkedList.

using System;
using System.Collections.Generic;

class Program {
  static void Main() {
    LinkedList<int> deque = new LinkedList<int>();

    // Adding elements to the front
    deque.AddFirst(1);
    deque.AddFirst(2);

    // Adding elements to the back
    deque.AddLast(3);
    deque.AddLast(4);

    // Removing elements from the front
    int front = deque.First.Value;
    deque.RemoveFirst();

    // Removing elements from the back
    int back = deque.Last.Value;
    deque.RemoveLast();

    foreach (int value in deque) {
      Console.WriteLine(value);
    }
  }
}

Output:

1
3

Implementing using List Class

List<T> deque = new List<T>();

• T: Specifies the element type.

Example 2

The below example shows how to implement deque using List.

using System;
using System.Collections.Generic;

class Program {
  static void Main() {
    List<int> deque = new List<int>();

    // Adding elements to the front
    deque.Insert(0, 1);
    deque.Insert(0, 2);

    // Adding elements to the back
    deque.Add(3);
    deque.Add(4);

    // Removing elements from the front
    int front = deque[0];
    deque.RemoveAt(0);

    // Removing elements from the back
    int back = deque[deque.Count - 1];
    deque.RemoveAt(deque.Count - 1);

    foreach (int value in deque) {
      Console.WriteLine(value);
    }
  }
}