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数据结构C#版线性表(Data Structure)之单链表(LinkList)

 2010-10-17 14:15:36 来源:WEB开发网   
核心提示:每个元素至少具有二个属性:data和next,data用来存放数据,数据结构C#版线性表(Data Structure)之单链表(LinkList),而next用来指出它后面的元素是谁(有点“指针”的意思),链表中的元素,下面是单链表的实现:using System;using System.T

每个元素至少具有二个属性:data和next。data用来存放数据,而next用来指出它后面的元素是谁(有点“指针”的意思)。

链表中的元素,通常也称为节点Node,下面是泛型版本的Node.cs

namespace 线性表
{
    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;
            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; }
        }
    }
}

链表在存储上并不要求所有元素按顺序存储,因为用节点的next就能找到下一个节点,这好象一根“用珠子串成的链子”,要找到其中的某一颗珠子,只要从第一

颗节点(通常称为Head节点)开始,不断根据next指向找到下一个,直到找到需要的节点为止。


链表中需要有一个Head节点做为开始,这跟顺序表有所不同,下面是单链表的实现:

using System;
using System.Text;

namespace 线性表
{
    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>
        /// 类索引器
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public T this[int index] 
        {
            get 
            {
                return this.GetItemAt(index);
            }
        }

        /// <summary>
        /// 返回单链表的长度
        /// </summary>
        /// <returns></returns>
        public int Count()
        {
            Node<T> p = head;
            int len = 0;
            while (p != null)
            {
                len++;
                p = p.Next;
            }
            return len;
        }

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

        /// <summary>
        /// 是否为空
        /// </summary>
        /// <returns></returns>
        public bool IsEmpty()
        {
            return head == null;
        }

        /// <summary>
        /// 在最后附加元素
        /// </summary>
        /// <param name="item"></param>
        public void Append(T item)
        {
            Node<T> d = new Node<T>(item);
            Node<T> n = new Node<T>();

            if (head == null)
            {
                head = d;
                return;
            }

            n = head;
            while (n.Next != null)
            {
                n = n.Next;
            }
            n.Next = d;
        }

        //前插
        public void InsertBefore(T item, int i)
        {
            if (IsEmpty() || i < 0)
            {
                Console.WriteLine("List is empty or Position is error!");
                return;
            }

            //在最开头插入
            if (i == 0)
            {
                Node<T> q = new Node<T>(item);
                q.Next = Head;//把"头"改成第二个元素
                head = q;//把自己设置为"头"
                return;
            }

            Node<T> n = head;
            Node<T> d = new Node<T>();
            int j = 0;

            //找到位置i的前一个元素d
            while (n.Next != null && j < i)
            {
                d = n;
                n = n.Next;
                j++;
            }

            if (n.Next == null) //说明是在最后节点插入(即追加)
            {
                Node<T> q = new Node<T>(item);
                n.Next = q;
                q.Next = null;
            }
            else
            {
                if (j == i)
                {
                    Node<T> q = new Node<T>(item);
                    d.Next = q;
                    q.Next = n;
                }
            }
        }

        /// <summary>
        /// 在位置i后插入元素item
        /// </summary>
        /// <param name="item"></param>
        /// <param name="i"></param>
        public void InsertAfter(T item, int i)
        {
            if (IsEmpty() || i < 0)
            {
                Console.WriteLine("List is empty or Position is error!");
                return;
            }

            if (i == 0)
            {
                Node<T> q = new Node<T>(item);
                q.Next = head.Next;
                head.Next = q;
                return;
            }

            Node<T> p = head;
            int j = 0;

            while (p != null && j < i)
            {
                p = p.Next;
                j++;
            }
            if (j == i)
            {
                Node<T> q = new Node<T>(item);
                q.Next = p.Next;
                p.Next = q;
            }
            else             
            {
                Console.WriteLine("Position is error!");
            }
        }

        /// <summary>
        /// 删除位置i的元素
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public T RemoveAt(int i)
        {
            if (IsEmpty() || i < 0)
            {
                Console.WriteLine("Link is empty or Position is error!");
                return default(T);
            }

            Node<T> q = new Node<T>();
            if (i == 0)
            {
                q = head;
                head = head.Next;
                return q.Data;
            }

            Node<T> p = head;
            int j = 0;

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

            if (j == i)
            {
                q.Next = p.Next;
                return p.Data;
            }
            else
            {
                Console.WriteLine("The node is not exist!");
                return default(T);
            }
        }

        /// <summary>
        /// 获取指定位置的元素
        /// </summary>
        /// <param name="i"></param>
        /// <returns></returns>
        public T GetItemAt(int i)
        {
            if (IsEmpty())
            {
                Console.WriteLine("List is empty!");
                return default(T);
            }

            Node<T> p = new Node<T>();
            p = head;

            if (i == 0) 
            { 
                return p.Data; 
            }

            int j = 0;

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

            if (j == i)
            {
                return p.Data;
            }
            else
            {
                Console.WriteLine("The node is not exist!");
                return default(T);
            }
        }

        //按元素值查找索引
        public int IndexOf(T value)
        {
            if (IsEmpty())
            {
                Console.WriteLine("List is Empty!");
                return -1;
            }
            Node<T> p = new Node<T>();
            p = head;
            int i = 0;
            while (!p.Data.Equals(value) && p.Next != null)
            {
                p = p.Next;
                i++;
            }
            return i;
        }

        /// <summary>
        /// 元素反转
        /// </summary>
        public void Reverse()
        {
            LinkList<T> result = new LinkList<T>();            
            Node<T> t = this.head;
            result.Head = new Node<T>(t.Data);
            t = t.Next;

            //(把当前链接的元素从head开始遍历,逐个插入到另一个空链表中,这样得到的新链表正好元素顺序跟原链表是相反的)
            while (t!=null)
            {                
                result.InsertBefore(t.Data, 0);
                t = t.Next;
            }
            this.head = result.head;//将原链表直接挂到"反转后的链表"上
            result = null;//显式清空原链表的引用,以便让GC能直接回收
        }


        public override string ToString()
        {
            StringBuilder sb = new StringBuilder();
            Node<T> n = this.head;
            sb.Append(n.Data.ToString() + ",");
            while (n.Next != null)
            {
                sb.Append(n.Next.Data.ToString() + ",");
                n = n.Next;
            }
            return sb.ToString().TrimEnd(',');

        }
    }
}

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Tags:数据结构 线性表 单链表

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