链表的C#代码实现

题目：　　1.在尾部增加元素

　　　　　2. 删除值为value的元素

　　　　　3.反转链表

思路：

增加和反转都没啥说的，就删除的时候需要考虑到的情况比较多，直接上代码，回头再分析

    class LinkNode<T>
    {
        public LinkNode<T> Next { get; set; }
        public T Value { get; set; }

        public LinkNode<T> AddNodeToEnd(T value, LinkNode<T> head)
        {
            if (value != null)
            {
                if (head == null)
                {
                    head = new LinkNode<T>();
                    head.Value = value;
                    head.Next = null;
                }
                else
                {
                    LinkNode<T> temp = head;
                    while (temp != null)
                    {
                        if (temp.Next == null)
                        {
                            temp.Next = new LinkNode<T>();
                            temp.Next.Value = value;
                            break;
                        }
                        temp = temp.Next;
                    }
                }
            }
            return head;
        }

        //public LinkNode<T> Remove(T value, LinkNode<T> head)
        //{
        //    LinkNode<T> pre = null;
        //    LinkNode<T> now = null;
        //    if (value != null)
        //    {
        //        if (head != null)
        //        {
        //            pre = head;
        //            if (head.Value.Equals(value) && head.Next == null)
        //            {
        //                head = null;
        //                return head;
        //            }
        //            if (head.Next != null) { now = head.Next; }
        //            while (now != null)
        //            {
        //                if (head.Value.Equals(value))
        //                {
        //                    head.Next = null;
        //                    head = now;
        //                    pre = head;
        //                    if (head.Next != null) { now = head.Next; }
        //                    else now = head; 
        //                }
        //                if (now.Value.Equals(value))
        //                {
        //                    if (now.Next != null)
        //                    {
        //                        LinkNode<T> next = now.Next;
        //                        pre.Next = next;
        //                        now.Next = null;
        //                        pre = pre.Next;
        //                        now = pre.Next;
        //                        continue;
        //                    }
        //                    else
        //                    {
        //                        if (pre == now) return null;
        //                        pre.Next = null;
        //                        break;
        //                    }
        //                }
        //                pre = now;
        //                now = now.Next;

        //            }
        //        }
        //    }
        //    return head;
        //}

        public LinkNode<T> Remove(T value, LinkNode<T> head)
        {
            LinkNode<T> pre = null;
            LinkNode<T> now = null;
            if (value != null)
            {
                if (head != null)
                {
                    //如果只有一个元素head
                    if (head.Next == null)
                    {
                        //如果head就是要找的那个
                        if (head.Value.Equals(value))
                        {
                            head = null;
                        }
                    }   
                    //如果有两个以上的元素                
                    else
                    {
                        pre = head;
                        now = head.Next;
                        while (now != null)
                        {
                            if (pre.Value.Equals(value))
                            {
                                //如果第一个就遇到了value
                                if (pre == head)
                                {
                                    head = head.Next;
                                    pre = head;
                                    if (pre == null) break;
                                    if (pre.Next != null) now = pre.Next;
                                    else now = pre;
                                }
                                else
                                {                                    
                                    if (now.Next != null)
                                    {
                                        pre.Next = now.Next;
                                        now = now.Next;
                                    }
                                    else break;
                                }
                            }
                            else
                            {
                                if (now.Value.Equals(value))
                                {
                                    if (now.Next != null && pre == head)
                                    {
                                        pre.Next = now.Next;
                                        now = pre.Next;
                                        continue;                                     
                                    }
                                    else if (now.Next != null)
                                    {
                                        now = now.Next;
                                    }                                    
                                    else pre.Next = null;
                                }
                                if (now.Next != null)
                                {
                                    now = now.Next;
                                    pre = pre.Next;
                                }
                                else break;
                            }
                                                      
                        }
                    }                   
                }
            }
            return head;
        }
        public LinkNode<T> Revert(LinkNode<T> head)
        {
            LinkNode<T> pre = null;
            LinkNode<T> now = null;
            LinkNode<T> next = null;

            if (head != null && head.Next != null)
            {
                pre = head;
                now = head.Next;
                while (now != null)
                {
                    if (pre == head && now.Next == null)
                    {
                        pre = head;
                        now.Next = pre;
                        head = now;
                        pre.Next = null;
                        return head;
                    }
                    else
                    {
                        if (pre == head)
                        {
                            pre.Next = null;
                        }
                        next = now.Next;
                        now.Next = pre;
                        pre = now;
                        now = next;
                    }
                }
                head = pre;
            }
            return head;
        }
    }

主函数：

 static void Main(string[] args)
        {
            LinkNode<string> s = new LinkNode<string>();
            s = s.AddNodeToEnd("1", null);
            s = s.AddNodeToEnd("2", s);
            s = s.AddNodeToEnd("3", s);
            s = s.AddNodeToEnd("5", s);
            s = s.AddNodeToEnd("1", s);
            s = s.Remove("3", s);
            s = s.Revert(s);
            Console.ReadKey();
        }