using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp8
{
    class SNode<T>  //結點，單鏈表
    {
        private T data;    //資料域
        private SNode<T> next;  //位置域

        public SNode(T val,SNode<T> p)  //普通結點
        {
            data = val;
            next = p;
        }
        public SNode(SNode<T> p)    //頭結點
        {
            next = p;
        }
        public SNode(T val) //尾結點
        {
            data = val;
            next = null;
        }
        public SNode() { }
        public T Data
        {
            get { return data; }
            set { data = value; }
        }
        public SNode<T> Next
        {
            get { return next; }
            set { next = value; }
        }
    }
    class SLinkList<T>:SNode<T>
    {
        private SNode<T> start;     //頭引用
        int length;     //單鏈表的長度

        //初始化單鏈表
        public SLinkList()
        {
            start = null;
        }
        //在單鏈表的末尾追加資料元素
        public void InsertNode(T a)
        {
            if (start == null)
            {
                start = new SNode<T>(a);
                length++;
                return;
            }
            SNode<T> current = start;
            while (current.Next != null)
            {
                current=current.Next;
            }
            current.Next = new SNode<T>(a);
            length++;
        }
        //在單鏈表的第i個數據元素的位置插入一個數據元素
        public void InsertNode(T a,int i)
        {
            SNode<T> current;   //當前結點
            SNode<T> previous;  //上一個結點
            if (i < 1 || i > length + 1)
            {
                Console.WriteLine("Position is error!");
                return;
            }
            SNode<T> newnode = new SNode<T>(a);
            //在空連結串列或第一個元素前插入第一個元素
            if (i == 1)
            {
                newnode.Next = start;
                start = newnode;
                length++;
                return;
            }
            //單鏈表的兩個元素之間插入一個元素
            current = start;
            previous = null;
            int j = 1;
            while (current!=null&&j<i)
            {
                previous = current;
                current = current.Next;
                j++;
            }
            if (j == i)
            {
                newnode.Next = current;
                previous.Next = newnode;
                length++;
            }
        }
        //刪除單鏈表的第i個數據元素
        public void DeleteNode(int i)
        {
            if (IsEmpty() || i < 1)
            {
                Console.WriteLine("Link is empty or Position is error!");
            }
            SNode<T> current = start;
            if (i == 1)
            {
                start = current.Next;
                length--;
                return;
            }
            SNode<T> previous = null;
            int j = 1;
            while (current.Next != null && j < i)
            {
                previous = current;
                current = current.Next;
                j++;
            }
            if (j == i)
            {
                previous.Next = current.Next;
                current = null;
                length--;
            }
            else
            {
                Console.WriteLine("The node is not exist!");
            }
        }
        //獲得單鏈表的第i個數據元素
        public T SearchNode(int i)
        {
            if (IsEmpty())
            {
                Console.WriteLine("List is empty!");
                return default(T);
            }
            SNode<T> current = start;
            int j = 1;
            while (current.Next != null && j < i) {
                current = current.Next;
                j++;
            }
            if (j == i)
            {
                return current.Data;
            }
            else
            {
                Console.WriteLine("The node is not exist!");
                return default(T);
            }
        }
        //在單鏈表中查詢值為value的資料元素
        public T SearchNode(T value)
        {
            if (IsEmpty())
            {
                Console.WriteLine("List is Empty!");
                return default(T);
            }
            SNode<T> current = start;
            while (!current.Data.ToString().Contains(value.ToString()) && current != null)
            {
                current = current.Next;
            }
            if (current != null)
            {
                return current.Data;
            }
            else
            {
                return default(T);
            }
        }
        //求單鏈表的長度
        public int GetLength()
        {
            return length;
        }
        //清空單鏈表
        public void Clear()
        {
            start = null;
        }
        //判斷單鏈表是否為空
        public bool IsEmpty()
        {
            if (start == null)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
        //列印連結串列元素
        public void print_f()
        {
            //Console.Clear();
            if (IsEmpty())
            {
                Console.WriteLine("List is empty!");
                return;
            }
            SNode<T> current = start;
            if (start == null)
            {
                Console.WriteLine("List is empty!");
                return;
            }
            while (current.Next != null)
            {
                Console.WriteLine(current.Data);
                current = current.Next;
            }
     
            Console.WriteLine(current.Data);

            Console.WriteLine("------------------------------");
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            SLinkList<string> str = new SLinkList<string>();
            str.InsertNode("a");    //末尾追加元素
            str.InsertNode("b");    //末尾追加元素
            str.InsertNode("c");    //末尾追加元素

            str.print_f();  //列印單鏈表

            str.InsertNode("1",1);  //在位置1插入元素1
            str.InsertNode("3", 3);  //在位置1插入元素3

            str.print_f();  //列印單鏈表

            str.DeleteNode(2);  //刪除第二個元素

            str.print_f();  //列印單鏈表

            Console.WriteLine("單鏈表的第3個元素:"+str.SearchNode(3));
            Console.WriteLine("單鏈表的長度為:"+str.GetLength());

            str.print_f();  //列印單鏈表


            str.Clear();    //清空連結串列

            str.print_f();  //列印單鏈表


            Console.ReadKey();

        }
    }
}