(精华)2020年8月27日 数据结构与算法解析(链表)
【摘要】
一：单链表实现原理
//链表类，包含链表定义及基本操作方法
public class MyLinkList<T>
{
private Node<T> head; //...
一：单链表实现原理
//链表类，包含链表定义及基本操作方法
public class MyLinkList<T>
{
private Node<T> head; //单链表的头结点
//头结点属性
public Node<T> Head
{
get
{
return head;
}
set
{
head = value;
}
}
//构造器
public MyLinkList()
{
head = null;
}
//求单链表的长度
public int GetLength()
{
Node<T> p = head;
int len = 0;
while (p != null)
{
++len;
p = p.Next;
}
return len;
}
//清空单链表
public void Clear()
{
head = null;
}
//判断单链表是否为空
public bool IsEmpty()
{
if (head == null)
{
return true;
}
else
{
return false;
}
}
//在单链表的末尾添加新元素
public void Append(T item)
{
Node<T> q = new Node<T>(item);
Node<T> p = new Node<T>();
if (head == null)
{
head = q;
return;
}
p = head;
while (p.Next != null)
{
p = p.Next;
}
p.Next = q;
}
//在单链表的第i个结点的位置前插入一个值为item的结点
public void Insert(T item, int i)
{
if (IsEmpty() || i < 1 || i > GetLength())
{
Console.WriteLine("LinkList is empty or Position is error!");
return;
}
if (i == 1)
{
Node<T> q = new Node<T>(item);
q.Next = head;
head = q;
return;
}
Node<T> p = head;
Node<T> r = new Node<T>();
int j = 1;
while (p.Next != null && j < i)
{
r = p;
p = p.Next;
++j;
}
if (j == i)
{
Node<T> q = new Node<T>(item);
q.Next = p;
r.Next = q;
}
}
//在单链表的第i个结点的位置后插入一个值为item的结点
public void InsertPost(T item, int i)
{
if (IsEmpty() || i < 1 || i > GetLength())
{
Console.WriteLine("LinkList is empty or Position is error!");
return;
}
if (i == 1)
{
Node<T> q = new Node<T>(item);
q.Next = head.Next;
head.Next = q;
return;
}
Node<T> p = head;
int j = 1;
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;
}
}
//删除单链表的第i个结点
public T Delete(int i)
{
if (IsEmpty() || i < 0 || i > GetLength())
{
Console.WriteLine("LinkList is empty or Position is error!");
return default(T);
}
Node<T> q = new Node<T>();
if (i == 1)
{
q = head;
head = head.Next;
return q.Data;
}
Node<T> p = head;
int j = 1;
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 " + i + "th node is not exist!");
return default(T);
}
}
//获得单链表的第i个数据元素
public T GetElem(int i)
{
if (IsEmpty() || i < 0)
{
Console.WriteLine("LinkList is empty or position is error! ");
return default(T);
}
Node<T> p = new Node<T>();
p = head;
int j = 1;
while (p.Next != null && j < i)
{
++j;
p = p.Next;
}
if (j == i)
{
return p.Data;
}
else
{
Console.WriteLine("The " + i + "th node is not exist!");
return default(T);
}
}
//在单链表中查找值为value的结点
public int Locate(T value)
{
if (IsEmpty())
{
Console.WriteLine("LinkList is Empty!");
return -1;
}
Node<T> p = new Node<T>();
p = head;
int i = 1;
while (!p.Data.Equals(value) && p.Next != null)
{
p = p.Next;
++i;
}
return i;
}
//显示链表
public void Display()
{
Node<T> p = new Node<T>();
p = this.head;
while (p != null)
{
Console.Write(p.Data + " ");
p = p.Next;
}
}
}
public class Program
{
static void Main(string[] args)
{
MyLinkList<string> myLinkList = new MyLinkList<string>(); //实例化一个单链表
Console.WriteLine(myLinkList.GetLength()); //获取长度
//添加元素
myLinkList.Append("good");
myLinkList.Append("monring");
myLinkList.Append("lwk");
myLinkList.Insert("!", 5); //在i结点前插元素，位置错误测试
myLinkList.InsertPost("!", 5); //在i结点后插元素，位置错误测试
myLinkList.InsertPost("!", 3); //后插元素
myLinkList.Insert(",", 3); //前插元素
myLinkList.Display(); //显示链表元素
Console.WriteLine(myLinkList.GetElem(4));//获取结点,并显示
myLinkList.Delete(1); //删除结点
myLinkList.Display();
Console.WriteLine(myLinkList.GetLength()); //显示链表长度
Console.Read();
}
}
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二：双向链表实现原理
using System;
using System.Text;
namespace 线性表
{
public class DbLinkList<T> : IListDS<T>
{
private DbNode<T> head;
public DbNode<T> Head
{
get { return head; }
set { head = value; }
}
public DbLinkList()
{
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()
{
DbNode<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)
{
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;
}
//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>
/// 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>
/// 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);
}
DbNode<T> p = new DbNode<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;
}
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>
/// 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
}
//得到某个指定的节点(为了下面测试从后向前遍历)
private DbNode<T> GetNodeAt(int i){
if (IsEmpty())
{
Console.WriteLine("List is empty!");
return null;
}
DbNode<T> p = new DbNode<T>();
p = head;
if (i == 0)
{
return p;
}
int j = 0;
while (p.Next != null && j < i)
{
j++;
p = p.Next;
}
if (j == i)
{
return p;
}
else
{
Console.WriteLine("The node is not exist!");
return null;
}
}
/// <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(',');
}
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(',');
}
}
}
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Console.WriteLine("-------------------------------------");
Console.WriteLine("双链表测试开始...");
DbLinkList<string> dblink = new DbLinkList<string>();
dblink.Head = new DbNode<string>("x");
dblink.InsertBefore("w", 0);
dblink.InsertBefore("v", 0);
dblink.Append("y");
dblink.InsertBefore("z", dblink.Count());
Console.WriteLine(dblink.Count());//5
Console.WriteLine(dblink.ToString());//v,w,x,y,z
Console.WriteLine(dblink[1]);//w
Console.WriteLine(dblink[0]);//v
Console.WriteLine(dblink[4]);//z
Console.WriteLine(dblink.IndexOf("z"));//4
Console.WriteLine(dblink.RemoveAt(2));//x
Console.WriteLine(dblink.ToString());//v,w,y,z
dblink.InsertBefore("x", 2);
Console.WriteLine(dblink.ToString());//v,w,x,y,z
Console.WriteLine(dblink.GetItemAt(2));//x
dblink.Reverse();
Console.WriteLine(dblink.ToString());//z,y,x,w,v
dblink.InsertAfter("1", 0);
dblink.InsertAfter("2", 1);
dblink.InsertAfter("6", 5);
dblink.InsertAfter("8", 7);
dblink.InsertAfter("A", 10);//Position is error!
Console.WriteLine(dblink.ToString()); //z,1,2,y,x,w,6,v,8
string _tail = dblink.GetItemAt(dblink.Count()-1);
Console.WriteLine(_tail);
Console.WriteLine(dblink.TestPrevErgodic());//8
Console.ReadKey(); //8,v,6,w,x,y,2,1,z
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双链表的插入操作要稍微复杂一点，示意图如下：
同样对于删除操作，也要额外处理prev指向
二：循环双向链表实现原理
代码就不贴了
文章来源: codeboy.blog.csdn.net，作者：愚公搬代码，版权归原作者所有，如需转载，请联系作者。
原文链接：codeboy.blog.csdn.net/article/details/108175845
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