链表

单链表

class Program
{
    static void Main(string[] args)
    {
        LinkedList<int> linkedList = new LinkedList<int>();
        Node<int> node1 = new Node<int> { Data = 1 };
        Node<int> node2 = new Node<int> { Data = 2 };
        Node<int> node3 = new Node<int> { Data = 3 };
        Node<int> node4 = new Node<int> { Data = 4 };
        linkedList.Append(node1);
        linkedList.Append(node2);
        linkedList.Append(node3);
        linkedList.Append(node4);
        linkedList.Insert(4, new Node<int> { Data = 0 });
        linkedList.Delete(2);
        linkedList.Display();

        //int length = linkedList.GetLength();
        //Console.WriteLine(length);

        Console.WriteLine(linkedList.GetDataByIndex(0).Data);
        Console.ReadKey();
    }
}

class LinkedList<T>
{
    public Node<T> Head { get; set; }

    public LinkedList()
    {
        Head = null;
    }

    #region 添加
    public void Append(Node<T> node)
    {
        Node<T> foot = node;

        if (Head == null)
        {
            Head = foot;
            return;
        }

        Node<T> A = Head;
        while (A.Next != null)
        {
            A = A.Next;
        }

        A.Next = foot;
    }
    #endregion

    #region 插入
    public void Insert(int index, Node<T> node)
    {
        if (Head == null || index > GetLength())
            return;

        if (index == 0)
        {
            Node<T> temp = Head;
            Head = node;
            Head.Next = temp;
            return;
        }

        //Node<T> previous = GetDataByIndex(index - 1);
        //node.Next = previous.Next;
        //previous.Next = node;

        Node<T> A = new Node<T>();
        Node<T> B = new Node<T>();
        B = Head;
        int j = 0;
        while (j < index)
        {
            A = B;
            B = B.Next;
            j++;
        }

        if (j == index)
        {
            Node<T> C = node;
            A.Next = C;
            C.Next = B;
        }
    }
    #endregion

    #region 删除
    public void Delete(int index)
    {
        if (Head == null || index >= GetLength())
            return;

        if (index == 0)
        {
            Head = Head.Next;
            return;
        }

        //Node<T> previous = GetDataByIndex(index - 1);
        //previous.Next = previous.Next.Next;

        Node<T> A = new Node<T>();
        Node<T> B = Head;
        int j = 0;
        while (B.Next != null && j < index)
        {
            A = B;
            B = B.Next;
            j++;
        }
        if (j == index)
            A.Next = B.Next;
    }
    #endregion

    #region 索引获取节点
    public Node<T> GetDataByIndex(int index)
    {
        if (index >= GetLength() || index < 0)
        {
            throw (new Exception("length out of range"));
        }

        if (index == 0)
            return Head;

        int count = 0;
        Node<T> temp = Head;
        while (temp.Next != null && count < index)
        {
            temp = temp.Next;
            count++;
        }

        return temp;
    }
    #endregion

    #region 长度
    public int GetLength()
    {
        if (Head == null)
            return 0;

        int length = 1;
        Node<T> A = Head;
        while (A.Next != null)
        {
            A = A.Next;
            length++;
        }

        return length;
    }
    #endregion

    #region 打印
    public void Display()
    {
        if (Head == null)
            return;

        Node<T> temp = Head;
        while (temp != null)
        {
            Console.WriteLine(temp.Data);
            temp = temp.Next;
        }
    }
    #endregion
}

class Node<T>
{
    public T Data { get; set; }
    public Node<T> Next { get; set; }

    public Node(T item)
    {
        this.Data = item;
        this.Next = null;
    }

    public Node()
    {
        this.Data = default(T);
        this.Next = null;
    }
}

---

双向链表

class Program
{
    static void Main(string[] args)
    {
        Node<int> node1 = new Node<int> { Data = 1 };
        Node<int> node2 = new Node<int> { Data = 2 };
        Node<int> node3 = new Node<int> { Data = 3 };
        Node<int> node4 = new Node<int> { Data = 4 };
        Node<int> node5 = new Node<int> { Data = 5 };

        DoublyLinkedList<int> doublyLinkedList = new DoublyLinkedList<int>();
        doublyLinkedList.Append(node1);
        doublyLinkedList.Append(node2);
        doublyLinkedList.Append(node3);
        doublyLinkedList.Append(node4);
        doublyLinkedList.Append(node5);

        doublyLinkedList.Insert(2, new Node<int> { Data = 9 });
        doublyLinkedList.Display();

        doublyLinkedList.Delete(2);
        Console.WriteLine("====================");
        doublyLinkedList.Display();

        //Console.WriteLine(doublyLinkedList.GetNodeByIndex(5).Data);

        //int length = doublyLinkedList.GetLength();
        //Console.WriteLine(length);

        Console.ReadKey();
    }
}

class DoublyLinkedList<T>
{
    public Node<T> Head { get; set; }

    #region 打印
    public void Display()
    {
        if (Head == null)
            return;

        Node<T> temp = Head;
        while (temp != null)
        {
            Console.WriteLine($"Prev: {temp.Prev?.Data.ToString() ?? string.Empty}" + ", "
                + $"Data: {temp.Data}" + ", "
                + $"Next: {temp.Next?.Data.ToString() ?? string.Empty}");
            temp = temp.Next;
        }
    }
    #endregion

    #region 长度
    public int GetLength()
    {
        if (Head == null)
            return 0;

        int count = 1;
        Node<T> temp = Head;
        while (temp.Next != null)
        {
            temp = temp.Next;
            count++;
        }

        return count;
    }
    #endregion

    #region 索引获取节点
    public Node<T> GetNodeByIndex(int index)
    {
        if (index < 0 || index >= GetLength())
            throw new Exception("index out of range");

        if (Head == null)
            return null;

        int count = 0;
        Node<T> temp = Head;
        while (temp.Next != null && count < index)
        {
            temp = temp.Next;
            count++;
        }

        return temp;
    }
    #endregion

    #region 添加
    public void Append(Node<T> node)
    {
        Node<T> foot = node;

        if (Head == null)
        {
            Head = foot;
            return;
        }

        Node<T> A = Head;
        while (A.Next != null)
        {
            A = A.Next;
        }

        A.Next = foot;
        foot.Prev = A;
    }
    #endregion

    #region 插入
    public void Insert(int index, Node<T> node)
    {
        if (Head == null && index == 0)
        {
            Head = node;
            return;
        }

        Node<T> A = new Node<T>();
        Node<T> B = Head;
        int j = 0;
        while (B.Next != null && j < index)
        {
            A = B;
            B = B.Next;
            j++;
        }
        if (j == index)
        {
            A.Next = node;
            B.Prev = node;
            node.Prev = A;
            node.Next = B;
        }
    }
    #endregion

    #region 删除
    public void Delete(int index)
    {
        if (Head == null)
            return;

        if (index < 0 || index >= GetLength())
            throw new Exception("index out of range");

        if (index == 0)
        {
            Head = Head.Next;
            Head.Prev = null;
            return;
        }

        Node<T> A = new Node<T>();
        Node<T> B = Head;
        int j = 0;
        while (B.Next != null && j < index)
        {
            A = B;
            B = B.Next;
            j++;
        }

        if (j == index)
        {
            A.Next = B.Next;
            B.Next.Prev = A;
        }
    } 
    #endregion
}

class Node<T>
{
    public T Data { get; set; }
    public Node<T> Prev { get; set; }
    public Node<T> Next { get; set; }
}

---

双向循环链表

class Program
{
    static void Main(string[] args)
    {
        Node<int> node1 = new Node<int> { Data = 1 };
        Node<int> node2 = new Node<int> { Data = 2 };
        Node<int> node3 = new Node<int> { Data = 3 };
        Node<int> node4 = new Node<int> { Data = 4 };
        Node<int> node5 = new Node<int> { Data = 5 };

        DoublyCircularLinkedList<int> doublyLinkedList = new DoublyCircularLinkedList<int>();
        doublyLinkedList.Append(node1);
        doublyLinkedList.Append(node2);
        doublyLinkedList.Append(node3);
        doublyLinkedList.Append(node4);
        doublyLinkedList.Append(node5);

        //doublyLinkedList.Insert(5, new Node<int> { Data = 9 });
        doublyLinkedList.Display();

        doublyLinkedList.Delete(4);
        Console.WriteLine("====================");
        doublyLinkedList.Display();

        //Console.WriteLine(doublyLinkedList.GetNodeByIndex(0).Data);

        //int length = doublyLinkedList.GetLength();
        //Console.WriteLine(length);

        Console.ReadKey();
    }
}

class DoublyCircularLinkedList<T>
{
    public Node<T> Head { get; set; }

    #region 打印
    public void Display()
    {
        if (Head == null)
            return;

        Node<T> temp = Head;
        while (temp != null)
        {
            Console.WriteLine($"Prev: {temp.Prev?.Data.ToString() ?? string.Empty}" + ", "
                + $"Data: {temp.Data}" + ", "
                + $"Next: {temp.Next?.Data.ToString() ?? string.Empty}");
            temp = temp.Next;
            if (temp == Head)
                return;
        }
    }
    #endregion

    #region 长度
    public int GetLength()
    {
        if (Head == null)
            return 0;

        int count = 1;
        Node<T> temp = Head;
        while (temp.Next != null && temp.Next != Head)
        {
            temp = temp.Next;
            count++;
        }

        return count;
    }
    #endregion

    #region 索引获取节点
    public Node<T> GetNodeByIndex(int index)
    {
        if (index < 0 || index >= GetLength())
            throw new Exception("index out of range");

        if (Head == null)
            return null;

        int count = 0;
        Node<T> temp = Head;
        while (temp.Next != null && count < index)
        {
            temp = temp.Next;
            count++;
        }

        return temp;
    }
    #endregion

    #region 添加
    public void Append(Node<T> node)
    {
        Node<T> foot = node;

        if (Head == null)
        {
            Head = foot;
            return;
        }

        Node<T> A = Head;
        while (A.Next != null && A.Next != Head)
        {
            A = A.Next;
        }

        A.Next = foot;
        foot.Prev = A;
        foot.Next = Head;
        Head.Prev = foot;
    }
    #endregion

    #region 插入
    public void Insert(int index, Node<T> node)
    {
        if (index < 0 || index >= GetLength())
            if (index == GetLength())
            {
                Append(node);
                return;
            }
            else
            {
                throw new Exception("index out of range");
            }

        if (Head == null)
        {
            if (index == 0)
            {
                Head = node;
                return;
            }
            else
            {
                throw new Exception("index out of range");
            }
        }

        if (index == 0)
        {
            Node<T> temp = Head;
            int i = GetLength();
            Node<T> foot = GetNodeByIndex(i - 1);
            Head = node;
            node.Next = temp;
            temp.Prev = node;
            node.Prev = foot;
            foot.Next = Head;
            return;
        }

        Node<T> A = new Node<T>();
        Node<T> B = Head;
        int j = 0;
        while (B.Next != null && j < index)
        {
            A = B;
            B = B.Next;
            j++;
        }
        if (j == index)
        {
            A.Next = node;
            B.Prev = node;
            node.Prev = A;
            node.Next = B;
        }
    }
    #endregion

    #region 删除
    public void Delete(int index)
    {
        if (Head == null)
            return;

        if (index < 0 || index >= GetLength())
            throw new Exception("index out of range");

        if (index == 0)
        {
            Node<T> foot = Head.Prev;
            Head = Head.Next;
            Head.Prev = foot;
            foot.Next = Head;
            return;
        }

        Node<T> A = new Node<T>();
        Node<T> B = Head;
        int j = 0;
        while (B.Next != null && j < index)
        {
            A = B;
            B = B.Next;
            j++;
        }

        if (j == index)
        {
            A.Next = B.Next;
            B.Next.Prev = A;
        }
    }
    #endregion
}

class Node<T>
{
    public T Data { get; set; }
    public Node<T> Prev { get; set; }
    public Node<T> Next { get; set; }
}