1 public class SingleLinkedList
  2     {
  3         //Inner class, represents a node of linked list. Each node consists of data and a link to next node
  4         class Node
  5         {
  6             public Node() { }
  7             public Node(object item)
  8             {
  9                 Data = item;
 10                 Next = null;
 11             }
 12             public object Data { get; set; }
 13             public Node Next { get; set; }
 14 
 15             public override string ToString()
 16             {
 17                 return "Node:" + Data.ToString();
 18             }
 19         }
 20 
 21         public SingleLinkedList()
 22         {
 23             header = null;
 24         }
 25 
 26         #region Public API
 27 
 28         //Add item before first node
 29         public void AddFirst(object item)
 30         {
 31             if (header == null)
 32             {
 33                 header = new Node(item);
 34             }
 35             else
 36             {
 37                 var newNode = new Node(item);
 38                 newNode.Next = header;
 39                 header = newNode;
 40             }
 41         }
 42 
 43         //Add item after last node
 44         public void AddLast(object item)
 45         {
 46             if (header == null)
 47             {
 48                 header = new Node(item);
 49             }
 50             else
 51             {
 52                 LastNode().Next = new Node(item);
 53             }
 54         }
 55 
 56         public void Insert(int index, object item)
 57         {
 58             if (index < 0) throw new ArgumentOutOfRangeException();
 59             if (index == 0)
 60             {
 61                 AddFirst(item);
 62                 return;
 63             }
 64             if (header == null) throw new ArgumentOutOfRangeException();
 65 
 66             var node = GetNode(index - 1);
 67             var newNode = new Node(item);
 68             newNode.Next = node.Next;
 69             node.Next = newNode;
 70         }
 71 
 72         public object Get(int index)
 73         {
 74             return GetNode(index).Data;
 75         }
 76 
 77         //Find index of specified data
 78         public int IndexOf(object item)
 79         {
 80             if (header == null) return -1;
 81 
 82             var curIndex = 0;
 83             for (var cur = new Node { Next = header }; cur.Next != null; cur = cur.Next, curIndex++)
 84             {
 85                 if (!cur.Next.Data.Equals(item)) continue;
 86                 return curIndex;
 87             }
 88 
 89             return -1;
 90         }
 91 
 92         //Remove specified data of its first occurance
 93         public void Remove(object item)
 94         {
 95             if (header == null) return;
 96 
 97             //Add a fake node pointing to header, so we don‘t need set up a local variable pointing to header. This is simple. Nice trick.
 98             for (var cur = new Node { Next = header }; cur.Next != null; cur = cur.Next)
 99             {
100                 if (!cur.Next.Data.Equals(item)) continue;
101                 if (cur.Next == header)
102                 {
103                     header = header.Next;
104                 }
105                 else
106                 {
107                     cur.Next = cur.Next.Next;
108                 }
109             }
110         }
111 
112         //此方法可以理解为先获取index-1位置的Node，然后设置此Node的下一个节点跳过index处的节点
113         public void RemoveAt(int index)
114         {
115             if (index < 0 || header == null) throw new ArgumentOutOfRangeException();
116             else if (index == 0)
117             {
118                 header = header.Next;
119             }
120             else
121             {
122                 Node pre = GetNode(index - 1);
123                 pre.Next = pre.Next.Next;
124             }
125         }
126 
127         public bool Contains(object item)
128         {
129             if (header == null) return false;
130             var current = header;
131             while (current != null && !current.Data.Equals(item))
132             {
133                 current = current.Next;
134             }
135             return current != null;
136         }
137 
138         public void Clear()
139         {
140             header = null;
141         }
142 
143         public bool IsEmpty()
144         {
145             return header == null;
146         }
147 
148         public int Count()
149         {
150             if (IsEmpty()) return 0;
151             int count = 1;
152             for (var cur = header; cur.Next != null; cur = cur.Next, count++)
153             {
154             }
155             return count;
156         }
157 
158         public override string ToString()
159         {
160             if (header == null) return "Empty";
161             StringBuilder sb = new StringBuilder();
162             for (Node current = header; current != null; current = current.Next)
163             {
164                 sb.Append(current.Data.ToString());
165                 if (current.Next != null) sb.Append("->");
166             }
167             return sb.ToString();
168         }
169 
170         #endregion
171 
172         #region Private Method
173 
174         private Node LastNode()
175         {
176             if (header == null) throw new InvalidOperationException();
177 
178             var current = header;
179             while (current.Next != null)
180             {
181                 current = current.Next;
182             }
183             return current;
184         }
185 
186         private Node GetNode(int index)
187         {
188             if (header == null) throw new ArgumentOutOfRangeException();
189 
190             int curIndex = 0;
191             var cur = header;
192             while (cur != null && curIndex != index)
193             {
194                 cur = cur.Next;
195                 curIndex++;
196             }
197 
198             if (cur == null)
199             {
200                 throw new ArgumentOutOfRangeException();
201             }
202             else
203             {
204                 return cur;
205             }
206         }
207 
208 
209         #endregion
210 
211         #region Fields
212 
213         private Node header;
214 
215         #endregion
216     }

 1 public static void Main(string[] args)
 2         {
 3             Can_Add_First();
 4             Can_Add_Last();
 5             Can_Insert();
 6             Other();
 7 
 8             Console.ReadKey();
 9         }
10 
11         static void Can_Add_First()
12         {
13             var list = new SingleLinkedList();
14             //add when list is empty
15             list.AddFirst("First");
16             Expect(list, "First");
17             //add when list is not empty
18             list.AddFirst("Second");
19             list.AddFirst("Third");
20             Expect(list, "Third->Second->First");
21         }
22 
23         static void Can_Add_Last()
24         {
25             var list = new SingleLinkedList();
26             //add when list is empty
27             list.AddLast("First");
28             Expect(list, "First");
29             //add when list is not empty
30             list.AddLast("Second");
31             list.AddLast("Third");
32             Expect(list, "First->Second->Third");
33         }
34 
35         static void Can_Insert()
36         {
37             var list = new SingleLinkedList();
38             //insert when list is empty
39             list.Insert(0, "First");
40             Expect(list, "First");
41             //insert when list is not empty
42             list.Insert(1, "Second");
43             Expect(list, "First->Second");
44             list.Insert(1, "Third");
45             Expect(list, "First->Third->Second");
46             list.Insert(0, "Forth");
47             Expect(list, "Forth->First->Third->Second");
48         }
49 
50         static void Other()
51         {
52             var list = new SingleLinkedList();
53             list.AddLast("First");
54             list.AddLast("Second");
55             list.AddLast("Third");
56             Console.WriteLine("object Get(int) Passed: " + (list.Get(1) as string == "Second"));
57             
58             Console.WriteLine("int IndexOf(object) Passsed: " + ((int)list.IndexOf("Third") == 2));
59             Console.WriteLine("int IndexOf(object) Passsed: " + ((int)list.IndexOf("Forth") == -1));
60             
61             list.Remove("First");
62             Expect(list, "Second->Third");
63             list.RemoveAt(1);
64             Expect(list, "Second");
65             
66             Console.WriteLine("bool Contains(object) Passed: " + (list.Contains("Second") == true));
67             Console.WriteLine("bool Contains(object) Passed: " + (list.Contains("First") == false));
68             Console.WriteLine("int Count() Passed: " + (list.Count() == 1));
69             Console.WriteLine("bool IsEmpty() Passed: " + (list.IsEmpty() == false));
70             
71             list.Clear();
72             Console.WriteLine("int Count() Passed: " + (list.Count() == 0));
73             Console.WriteLine("bool IsEmpty() Passed: " + (list.IsEmpty() == true));
74         }