C#数据结构－链表

理论基础：

链表是用一组任意的存储单元来存储线性表中的数据元素。

如果结点的引用域只存储该结点直接后继结点的存储地址，则该链表叫单链表(Singly Linked List)。

单链表由头引用H唯一确定。头引用指向单链表的第一个结点，也就是把单链表第一个结点的地址放在H中。

C#实现：

1接口

引用线性表的接口IListDS<T>

2实现

首先，必须定义一个单链表的节点类
public class Node<T>
{
    private T data;        //数据域
    private Node<T> next;  //引用域

    public Node(T val)
    {
        data = val;
        next = null;
    }

    public Node()
    {
        data = default(T);
        next = null;
    }

    public T Data
    {
        get { return data; }
        set { data = value; }
    }
    public Node<T> Next
    {
        get { return next; }
        set { next = value; }
    }
}
实现主体类

Append,Insert,InsertBack三个方法实质上都是插入操作，可以考虑用overload或者override来实现，有兴趣的朋友试试。
public class LinkList<T> : IListDS<T>
{
    private Node<T> head;

    public Node<T> Head
    {

        get { return head; }
        set { head = value; }
    }
    public LinkList()
    {
        head = null;
    }

    /// <summary>
    /// 获取长度
    /// </summary>
    /// <returns></returns>
    public int GetLength()
    {
        Node<T> p = head;
        int len = 0;
        while (p != null)
        {
            ++len;
            p = p.Next;
        }
        return len;
    }

    /// <summary>
    /// 清空操作
    /// </summary>
    public void Clear()
    {
        head = null;
    }

    /// <summary>
    /// 判断线性表是否为空
    /// </summary>
    /// <returns></returns>
    public bool IsEmpty()
    {
        if (head == null)
        {
            return true;
        }
        else
        {
            return false;
        }
    }

    /// <summary>
    /// 附加操作,线性表未满，将值为item的新元素添加到末尾
    /// </summary>
    /// <param name="item"></param>
    public void Append(T item)
    {
        Node<T> newNode = new Node<T>(item);  //根据元素创建新的节点
        Node<T> node = new Node<T>();

        if (head == null)
        {
            head = newNode;
            return;
        }
        node = head;
        while (node.Next != null)
        {
            node = node.Next;
        }
        node.Next = newNode;
    }

    /// <summary>
    /// 寻找节点
    /// </summary>
    /// <param name="i"></param>
    /// <returns></returns>
    public Node<T> FindNode(int i)
    {
        if (IsEmpty())
        {
            Console.Write("List is empty");
            return null;
        }
        if (i < 1)
        {
            Console.Write("Index is error");
            return null;
        }
        Node<T> current = head;
        int j = 1;

        while (current.Next != null && j < i)
        {
            ++j;
            current = current.Next;
        }
        return current;
    }

    /// <summary>
    /// 插入操作,在第i个节点前面插入item
    /// </summary>
    /// <param name="item"></param>
    /// <param name="i"></param>
    public void Insert(T item, int i)
    {
        Node<T> newNode = new Node<T>(item);
        Node<T> node = new Node<T>();
        Node<T> current = FindNode(i);
        if (current != null)
        {
            node = current;       //对目标节点备份
            newNode.Next = current;
            node.Next = newNode;
        }
    }

    /// <summary>
    /// 插入操作,在第i个节点后面插入item
    /// </summary>
    /// <param name="item"></param>
    /// <param name="i"></param>
    public void InsertBack(T item, int i)
    {
        Node<T> newNode = new Node<T>(item);
        Node<T> current = FindNode(i);
        if (current != null)
        {
            newNode.Next = current.Next;
            current.Next = newNode;
        }
    }

    /// <summary>
    /// 删除操作
    /// </summary>
    /// <param name="i"></param>
    /// <returns></returns>
    public T Delete(int i)
    {
        Node<T> current = FindNode(i);
        Node<T> node = new Node<T>();
        if (current != null)
        {
            node = current;   //对目标节点备份
            node.Next = current.Next;
            return current.Data;
        }
        else
        {
            Console.Write("the node is not exist!");
            return default(T);
        }
    }

    /// <summary>
    /// 去表元
    /// </summary>
    /// <param name="i"></param>
    /// <returns></returns>
    public T GetElem(int i)
    {
        Node<T> current = FindNode(i);

        if (current != null)
        {
            return current.Data;
        }
        else
        {
            Console.Write("the node is not exist!");
            return default(T);
        }
    }

    /// <summary>
    /// 按值查找
    /// </summary>
    /// <param name="value"></param>
    /// <returns></returns>
    public int Locate(T value)
    {
        if (IsEmpty())
        {
            Console.WriteLine("List is Empty!");
            return -1;
        }
        Node<T> current = new Node<T>();
        current = head;
        int i = 1;
        while (current.Next != null && !current.Data.Equals(value))
        {
            current = current.Next;
            ++i;
        }
        return i;
    }
}