namespace 线性表
{
  public interface IListDS<T>
  {
    //取得线性表的实际元素个数
    int Count();
    //清空线性表
    void Clear();
    //判断线性表是否为空
    bool IsEmpty();
    //（在末端）追加元素
    void Append(T item);
    //在位置i“前面”插入元素item
    void InsertBefore(T item, int i);
    //在位置i“后面”插入元素item
    void InsertAfter(T item, int i);
    //删除索引i处的元素
    T RemoveAt(int i);
    //获得索引位置i处的元素
    T GetItemAt(int i);
    //返回元素value的索引
    int IndexOf(T value);
    //反转线性表的所有元素
    void Reverse();
  }
}

using System;
using System.Text;
namespace 线性表
{
  /// <summary>
  /// 顺序表
  /// </summary>
  /// <typeparam name="T"></typeparam>
  public class SeqList<T> : IListDS<T>
  {
    private int maxsize;
    private T[] data;
    private int last;
    //类索引器
    public T this[int index]
    {
      get
      {
        return this.GetItemAt(index);
      }
      set
      {
        if (index < 0 || index > last + 1)
        {
          Console.WriteLine("Position is error");
          return;
        }
        data[index] = value;
      }
    }
    //最后一个元素的下标
    public int Last
    {
      get { return last; }
    }
    //最大容量
    public int Maxsize
    {
      get { return this.maxsize; }
      set { this.maxsize = value; }
    }
    //构造函数
    public SeqList(int size)
    {
      data = new T[size];
      maxsize = size;
      last = -1;
    }
    //返回链表的实际长度
    public int Count()
    {
      return last + 1;
    }
    //清空
    public void Clear()
    {
      last = -1;
    }
    //是否空
    public bool IsEmpty()
    {
      return last == -1;
    }
    //是否满
    public bool IsFull()
    {
      return last == maxsize - 1;
    }
    //(在最后位置)追加元素
    public void Append(T item)
    {
      if (IsFull())
      {
        Console.WriteLine("List is full");
        return;
      }
      data[++last] = item;
    }
    /// <summary>
    ///前插
    /// </summary>
    /// <param name="item">要插入的元素</param>
    /// <param name="i">要插入的位置索引</param>
    public void InsertBefore(T item, int i)
    {
      if (IsFull())
      {
        Console.WriteLine("List is full");
        return;
      }
      if (i < 0 || i > last + 1)
      {
        Console.WriteLine("Position is error");
        return;
      }
      if (i == last + 1)
      {
        data[last + 1] = item;
      }
      else
      {
        //位置i及i以后的元素，全部后移
        for (int j = last; j >= i; j--)
        {
          data[j + 1] = data[j];
        }
        data[i] = item;
      }
      ++last;
    }
    /// <summary>
    /// 后插
    /// </summary>
    /// <param name="item"></param>
    /// <param name="i"></param>
    public void InsertAfter(T item, int i) 
    {
      if (IsFull())
      {
        Console.WriteLine("List is full");
        return;
      }
      if (i < 0 || i > last)
      {
        Console.WriteLine("Position is error");
        return;
      }
      if (i == last)
      {
        data[last + 1] = item;
      }
      else
      {
        //位置i以后的元素(不含位置i)，全部后移
        for (int j = last; j > i; j--)
        {
          data[j + 1] = data[j];
        }
        data[i+1] = item;
      }
      ++last;
    }
    /// <summary>
    /// 删除元素
    /// </summary>
    /// <param name="i">要删除的元素索引</param>
    /// <returns></returns>
    public T RemoveAt(int i)
    {
      T tmp = default(T);
      if (IsEmpty())
      {
        Console.WriteLine("List is empty");
        return tmp;
      }
      if (i < 0 || i > last)
      {
        Console.WriteLine("Position is error!");
        return tmp;
      }
      if (i == last)
      {
        tmp = data[last];
      }
      else
      {
        tmp = data[i];
        //位置i以及i以后的元素前移
        for (int j = i; j <= last; j++)
        {
          data[j] = data[j + 1];
        }
      }
      --last;
      return tmp;
    }
    /// <summary>
    /// 获取第几个位置的元素
    /// </summary>
    /// <param name="i">第几个位置</param>
    /// <returns></returns>
    public T GetItemAt(int i)
    {
      if (IsEmpty() || (i < 0) || (i > last))
      {
        Console.WriteLine("List is empty or Position is error!");
        return default(T);
      }
      return data[i];
    }
    /// <summary>
    /// 定位元素的下标索引
    /// </summary>
    /// <param name="value"></param>
    /// <returns></returns>
    public int IndexOf(T value)
    {
      if (IsEmpty())
      {
        Console.WriteLine("List is Empty!");
        return -1;
      }
      int i = 0;
      for (i = 0; i <= last; i++)
      {
        if (value.Equals(data[i]))
        {
          break;
        }
      }
      if (i > last)
      {
        return -1;
      }
      return i;
    }
    /// <summary>
    /// 元素反转
    /// </summary>
    public void Reverse()
    {
      T tmp = default(T);
      for (int i = 0; i <= last / 2; i++)
      {
        tmp = data[i];
        data[i] = data[last-i];
        data[last-i] = tmp;
      }
    }
    public override string ToString()
    {
      StringBuilder sb = new StringBuilder();
      for (int i = 0; i <= last; i++)
      {
        sb.Append(data[i].ToString() + "，");
      }
      return sb.ToString().TrimEnd('，');
    }
  }
}

Console.WriteLine("顺序表测试开始...");
SeqList<string> seq = new SeqList<string>(10);
seq.Append("x");
seq.InsertBefore("w", 0);
seq.InsertBefore("v", 0);
seq.Append("y");
seq.InsertBefore("z", seq.Count());
Console.WriteLine(seq.Count());//5
Console.WriteLine(seq.ToString());//v,w,x,y,z
Console.WriteLine(seq[1]);//w
Console.WriteLine(seq[0]);//v
Console.WriteLine(seq[4]);//z
Console.WriteLine(seq.IndexOf("z"));//4
Console.WriteLine(seq.RemoveAt(2));//x
Console.WriteLine(seq.ToString());//v,w,y,z
seq.InsertBefore("x", 2);      
Console.WriteLine(seq.ToString());//v,w,x,y,z
Console.WriteLine(seq.GetItemAt(2));//x
seq.Reverse();
Console.WriteLine(seq.ToString());//z,y,x,w,v
seq.InsertAfter("z_1", 0);
seq.InsertAfter("y_1", 2);
seq.InsertAfter("v_1", seq.Count()-1);
Console.WriteLine(seq.ToString());//z，z_1，y，y_1，x，w，v，v_1