C# 数据结构与算法系列(三) 线性表之链表

线性表的链存储称为链表。特点：存储单元上非连续、非顺序的存储结构，数据元素的逻辑顺序是通过链表中的指针链接次序实现的。
链表由一系列结点（链表中每一个元素称为结点）组成，结点可以在运行时动态生成。每个结点包括两个部分：一个是存储数据元素
的数据域，另一个是存储下一个结点地址的指针域。
链表有单链表,双向链表等
下面介绍单链表的实现方法：

public class Node<T>
    {
        private T data;
        private Node<T> next;

        public Node(T val, Node<T> p)
        {
            data = val;
            next = p;
        }
        public Node(Node<T> p)
        {
            next = p;
        }
        public Node(T val)
        {
            data = val;
        }
        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; }
        }
    }

    public class LinkList<T>
    {
        private Node<T> head;
        public Node<T> Head
        {
            get { return head; }
            set { head = value; }
        }
        public LinkList()
        {
            head = null;
        }
        public int GetLength()
        {
            Node<T> p = head;
            int len = 0;
            while (p != null)
            {
                ++len;
                p = p.Next;
            }
            return len;
        }
        public void clear()
        {
            head = null;
        }
        public bool isEmpty()
        {
            if (head == null)
                return true;
            else
                return false;
        }
        public void Append(T item)
        {
            Node<T> q = new Node<T>(item);
            Node<T> p = new Node<T>();
            if (head == null)
            {
                head = q;
                return;
            }
            p = head;
            while (p.Next != null)
            {
                p = p.Next;   //把位置定义在最后
            }
            p.Next = q;       //添加元素
        }
        public void Insert(T item, int i)
        {
            if (isEmpty() || i < 1)
            {
                throw new Exception("Insert: Error!");
            }
            if (i == 1)
            {
                Node<T> q = new Node<T>(item);
                q.Next = head;
                head = q;
                return;
            }
            Node<T> p = head;
            Node<T> r = new Node<T>();
            int j = 1;
            while (p.Next != null && j < i)
            {
                r = p;
                p = p.Next;
                ++j;
            }
            if (j == i)
            {
                Node<T> q = new Node<T>(item);
                q.Next = p;
                r.Next = q;
            }
            else
            {
                throw new Exception("Insert: Error");
            }
        }
        public T Delete(int i)
        {
            if (isEmpty() && i < 0)
            {
                throw new Exception("Error");
            }
            Node<T> q = new Node<T>();
            if (i == 1)
            {
                q = head;
                head = head.Next;
                return q.Data;
            }
            Node<T> p = head;
            int j = 1;
            while (p.Next != null && j < i)
            {
                ++j;
                q = p;
                p = p.Next;
            }
            if (j == i)
            {
                q.Next = p.Next;
                return p.Data;
            }
            else
            {
                return default(T);
            }
        }
        public T GetElem(int i)
        {
            if (isEmpty())
            {
                return default(T);
            }
            Node<T> p = new Node<T>();
            p = head;
            int j = 1;
            while (p.Next != null && j < i)
            {
                ++j;
                p = p.Next;
            }
            if (j == i)
            {
                return p.Data;
            }
            else
            {
                return default(T);
            }
        }
        public int Locate(T value)
        {
            if (isEmpty())
            {
                return -1;
            }
            Node<T> p = new Node<T>();
            p = head;
            int i = 1;
            while (!p.Data.Equals(value) && p.Next != null)
            {
                p = p.Next;
                ++i;
            }
            return i;
        }
    }

下面代码来使用链表
 

private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                LinkList<string> str = new LinkList<string>();
                str.Head = new Node<string> ("A");
                str.Append("B");
                str.Append("D");
                str.Append("E");
                str.Insert("C", 5);
                
                richTextBox1.Text = str.GetElem(1) + str.GetElem(2) + str.GetElem(3) + str.GetElem(4) + str.GetElem(5);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }