/// <summary>
/// 返回单链表的长度
/// </summary>
/// <returns></returns>
public int Count()
{
DbNode <T> p = head;
int len = 0;
while (p != null)
{
len++;
p = p.Next;
}
return(len);
}
public override string ToString()
{
StringBuilder sb = new StringBuilder();
DbNode <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(','));
}
/// <summary>
/// 测试用prev属性从后面开始遍历
/// </summary>
/// <returns></returns>
public string TestPrevErgodic()
{
DbNode <T> tail = GetNodeAt(Count() - 1);
StringBuilder sb = new StringBuilder();
sb.Append(tail.Data.ToString() + ",");
while (tail.Prev != null)
{
sb.Append(tail.Prev.Data.ToString() + ",");
tail = tail.Prev;
}
return(sb.ToString().TrimEnd(','));
}
//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)
{
DbNode <T> q = new DbNode <T>(item);
q.Next = head; //把"头"改成第二个元素
head.Prev = q;
head = q; //把自己设置为"头"
return;
}
DbNode <T> n = head;
DbNode <T> d = new DbNode <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)
{
DbNode <T> q = new DbNode <T>(item);
n.Next = q;
q.Prev = n;
q.Next = null;
}
else
{
if (j == i)
{
DbNode <T> q = new DbNode <T>(item);
d.Next = q;
q.Prev = d;
q.Next = n;
n.Prev = q;
}
}
}
/// <summary>
/// 元素反转
/// </summary>
public void Reverse()
{
DbLinkList <T> result = new DbLinkList <T>();
DbNode <T> t = this.head;
result.Head = new DbNode <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
}
/// <summary>
/// 在最后附加元素
/// </summary>
/// <param name="item"></param>
public void Append(T item)
{
DbNode <T> d = new DbNode <T>(item);
DbNode <T> n = new DbNode <T>();
if (head == null)
{
head = d;
return;
}
n = head;
while (n.Next != null)
{
n = n.Next;
}
n.Next = d;
d.Prev = n;
}
//按元素值查找索引
public int IndexOf(T value)
{
if (IsEmpty())
{
Console.WriteLine("List is Empty!");
return(-1);
}
DbNode <T> p = new DbNode <T>();
p = head;
int i = 0;
while (!p.Data.Equals(value) && p.Next != null)
{
p = p.Next;
i++;
}
return(i);
}
/// <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)
{
DbNode <T> q = new DbNode <T>(item);
q.Next = head.Next;
head.Next.Prev = q;
head.Next = q;
q.Prev = head;
return;
}
DbNode <T> p = head;
int j = 0;
while (p != null && j < i)
{
p = p.Next;
j++;
}
if (j == i)
{
DbNode <T> q = new DbNode <T>(item);
q.Next = p.Next;
if (p.Next != null)
{
p.Next.Prev = q;
}
p.Next = q;
q.Prev = p;
}
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));
}
DbNode <T> q = new DbNode <T>();
if (i == 0)
{
q = head;
head = head.Next;
head.Prev = null;
return(q.Data);
}
DbNode <T> p = head;
int j = 0;
while (p.Next != null && j < i)
{
j++;
q = p;
p = p.Next;
}
if (j == i)
{
p.Next.Prev = q;
q.Next = p.Next;
return(p.Data);
}
else
{
Console.WriteLine("The node is not exist!");
return(default(T));
}
}
/// <summary>
/// 清空
/// </summary>
public void Clear()
{
head = null;
}
public DbLinkList()
{
head = null;
}
public DbNode()
{
data = default(T);
next = null;
prev = null;
}
public DbNode(T data)
{
this.data = data;
this.next = null;
this.prev = null;
}
public DbNode(DbNode <T> next)
{
this.data = default(T);
this.next = next;
this.prev = null;
}
public DbNode(T data, DbNode <T> next)
{
this.data = data;
this.next = next;
this.prev = null;
}
public DbNode(T data, DbNode <T> next, DbNode <T> prev)
{
this.data = data;
this.next = next;
this.prev = prev;
}
