在单链表中，我们需要在内部有一个头节点，我们可以通过这个头节点找到其他的节点，相当于一个线索。
纵观顺序结构的线性表和单链表的实现，难点基本上都在于添加和删除操作。基于数组的线性表中，数组的索引就相当于是线性表的序号，但在单链表中，我们没有序号这个东西，所以在添加和删除操作中，我们需要先找到指定的元素，然后才能继续进行操作。在插入操作中，我们需要同时保存有当前节点的前一个节点和当前的节点，因为当前要插入的节点要放在前一个节点的Next引用域，而当前节点要放在要插入节点的next域。删除节点与此相似。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace DataStructure
{
class LinkList<T> : IListDS<T>
{
class Node<T>
{
private T data;
/// <summary>
/// 数据域
/// </summary>
public T Data
{
get { return data; }
set { data = value; }
}
private Node<T> next;
/// <summary>
/// 引用域
/// </summary>
public Node<T> Next
{
get { return next; }
set { next = value; }
}
//头结点构造函数
public Node(Node<T> node)
: this(default(T), node)
{
}
//普通结点构造函数
public Node(T data, Node<T> node)
{
this.Data = data;
this.Next = node;
}
/// <summary>
/// 空构造函数
/// </summary>
public Node()
: this(default(T), null)
{
}
//尾结点构造函数
public Node(T data)
: this(data, null)
{
}
}
private Node<T> Head;
public LinkList()
{
}
public int Lenth
{
get { return this.GetLength(); }
}
public LinkList(T[] t)
{
this.Head = new Node<T>(t[0]);
Node<T> Last;
Last = Head;
for (int i = 1; i < t.Length; i++)
{
//尾插入法
Last.Next = new Node<T>(t[i]);
Last = Last.Next;
}
}
public States Append(T item)
{
//(1)头结点没有
if (Head==null)
{
Head = new Node<T>(item);
}
//(2)正常的插入情况
Node<T> Last;
Last=Head;
//遍历到最后一个结点，在最后一个结点附加上
while (null!=Last.Next)
{
Last = Last.Next;
}
Last.Next = new Node<T>(item);
return States.Success;
}
public void Clear()
{
this.Head = null;
}
public T Delete(int index, out States states)
{
bool isIndexTrue = index < 0 || index >= this.GetLength();
if (IsEmpty() == true || isIndexTrue)
{
states = States.Fail;
return default(T);
}
//找到指定的结点
Node<T> Current = Head;
Node<T> Previous = Head;
int Count = 0;
while (Count != index && Current.Next != null)
{
Previous = Current;
Current = Current.Next;
Count++;
}
T ValueToDel = Current.Data;
//是否是头结点
if (Count == 0)
{
Head = Current.Next;
}
//是否是普通的结点
if (Count != 0 && Current.Next != null)
{
Previous.Next = Current.Next;
}
//是否是最后一个结点
if (Count != 0 && Current.Next == null)
{
Previous.Next = null;
}
//删除结点
states = States.Success;
return ValueToDel;
}
public T GetElem(int i)
{
if (i < 0 || i >= this.GetLength())
{
return default(T);
}
if (IsEmpty() == true)
{
return default(T);
}
Node<T> Last = Head;
int Count = 0;
while (Count != i && Last.Next != null)
{
Last = Last.Next;
Count++;
}
return Last.Data;
}
public int GetLength()
{
if (Head==null)
{
return 0;
}
Node<T> Last;
Last = Head;
int Count=0;
while (Last.Next!=null)
{
Last = Last.Next;
Count++;
}
return ++Count;
//throw new NotImplementedException();
}
public States Insert(T item, int index)
{
bool isIndexTrue = index < 0 || index > this.GetLength();
if (isIndexTrue)
{
return States.Fail;
}
//如果链表为空
if (IsEmpty() == true )
{
Head.Data = item;
}
//如果是第一个结点
if (index==0)
{
Node<T> node = new Node<T>(item);
node.Next = Head;
Head = node;
}
//如果是普通的结点
Node<T> Previous = Head;
// Node<T> Previous = Head;
int Count = 0;
while (Count != index-1 && Previous.Next != null)
{
// Previous = Current;
Previous = Previous.Next;
Count++;
}
if (Count == index-1)
{
Node<T> node=new Node<T>(item);
node.Next = Previous.Next;
Previous.Next = node;
}
//如果是最后一个结点
if (this.GetLength()==index)
{
Previous.Next = new Node<T>(item);
}
return States.Success;
}
public bool IsEmpty()
{
return Head == null ? true : false;
}
public int Locate(T value, out States states)
{
if (IsEmpty() == true)
{
states = States.Fail;
return 0;
}
Node<T> Last = Head;
int Count = 0;
while (Last.Next != null &&( !value.Equals(Last.Data)))
{
Last = Last.Next;
Count++;
}
states = States.Success;
return Count;
}
}
}
来源：https://www.cnblogs.com/kissazi2/p/3193957.html