C#数据结构之堆栈(Stack)实例详解

本文实例讲述了c#数据结构之堆栈(stack)。分享给大家供大家参考，具体如下：

堆栈(stack)最明显的特征就是“先进后出”，本质上讲堆栈也是一种线性结构，符合线性结构的基本特点：即每个节点有且只有一个前驱节点和一个后续节点。

相对前面学习过的、不同的地方在于：stack把所有操作限制在"只能在线性结构的某一端"进行，而不能在中间插入或删除元素。下面是示意图：

从示意图中可以看出，堆栈有二种实现方式：基于数组的顺序堆栈实现、类似链表的链式堆栈实现

先抽象堆栈的接口istack:

namespace 栈与队列
{
  public interface istack<t>
  {
    /// <summary>
    /// 返回堆栈的实际元素个数
    /// </summary>
    /// <returns></returns>
    int count();
    /// <summary>
    /// 判断堆栈是否为空
    /// </summary>
    /// <returns></returns>
    bool isempty();
    /// <summary>
    /// 清空堆栈里的元素
    /// </summary>
    void clear();
    /// <summary>
    /// 入栈：将元素压入堆栈中
    /// </summary>
    /// <param name="item"></param>
    void push(t item);
    /// <summary>
    /// 出栈：从堆栈顶取一个元素，并从堆栈中删除
    /// </summary>
    /// <returns></returns>
    t pop();
    /// <summary>
    /// 取堆栈顶部的元素(但不删除)
    /// </summary>
    /// <returns></returns>
    t peek();
  }
}

顺序堆栈(seqstack)的实现：

using system;
using system.text;
namespace 栈与队列
{
  public class seqstack<t>:istack<t>
  {
    private int maxsize;
    private t[] data;
    private int top;    
    public seqstack(int size) 
    {
      data = new t[size];
      maxsize = size;
      top = -1;
    }
    #region //接口实现部分
    public int count() 
    {
      return top + 1;
    }
    public void clear() 
    {
      top = -1;
    }
    public bool isempty() 
    {
      return top == -1;
    }
    public void push(t item)
    {
      if (isfull())
      {
        console.writeline("stack is full");
        return;
      }
      data[++top] = item;
    }
    public t pop()
    {
      t tmp = default(t);
      if (isempty())
      {
        console.writeline("stack is empty");
        return tmp;
      }
      tmp = data[top];
      top--;
      return tmp;
    }
    public t peek()
    {
      if (isempty())
      {
        console.writeline("stack is empty!");
        return default(t);
      }
      return data[top];
    }
    #endregion
    public bool isfull() 
    {
      return top == maxsize - 1;
    }
    public override string tostring()
    {
      stringbuilder sb = new stringbuilder();
      for (int i = top;i>=0;i--)
      {
        sb.append(data[i] + ",");
      }
      return sb.tostring().trim(',');
    }    
  }
}

链式堆栈(linkstack)的实现

先定义节点node.cs

namespace 栈与队列
{
  public class node<t>
  {
    private t data;
    private node<t> next;
    public node(t data, node<t> next) 
    {
      this.data = data;
      this.next = next;
    }
    public node(node<t> next) 
    {
      this.next = next;
      this.data = default(t);
    }
    public node(t data) 
    {
      this.data = data;
      this.next = null;
    }
    public node() 
    {
      this.data = default(t);
      this.next = null;
    }
    public t data {
      get { return this.data; }
      set { this.data = value; }
    }
    public node<t> next 
    {
      get { return next; }
      set { next = value; }
    }
  }
}

下面是linkstack.cs

using system;
using system.text;
namespace 栈与队列
{
  public class linkstack<t>:istack<t>
  {
    private node<t> top;
    private int num;//节点个数
    /// <summary>
    /// 顶部节点
    /// </summary>
    public node<t> top 
    {
      get { return top; }
      set { top = value; }
    }
    public linkstack() 
    {
      top = null;
      num = 0;
    }
    public int count() 
    {
      return num;
    }
    public void clear() 
    {
      top = null;
      num = 0;
    }
    public bool isempty() 
    {
      if (top == null && num == 0)
      {
        return true;
      }
      else
      {
        return false;
      }
    }
    public void push(t item) 
    {
      node<t> q = new node<t>(item);
      if (top == null)
      {
        top = q;
      }
      else
      {
        q.next = top;
        top = q;
      }
      num++;
    }
    public t pop() 
    {
      if (isempty()) 
      {
        console.writeline("stack is empty!");
        return default(t);
      }
      node<t> p = top;
      top = top.next;
      num--;
      return p.data;
    }
    public t peek() 
    {
      if (isempty()) 
      {
        console.writeline("stack is empty!");
        return default(t);
      }
      return top.data;
    }
    public override string tostring()
    {
      stringbuilder sb = new stringbuilder();
      if (top != null) 
      {
        sb.append(top.data.tostring() + ",");
        node<t> p = top;
        while (p.next != null)
        {          
          sb.append(p.next.data.tostring()+ ",");
          p = p.next;
        }
      }
      return sb.tostring();
    }
  }
}

测试代码片段：

console.writeline("顺序堆栈测试开始...");
seqstack<int> seqstack = new seqstack<int>(10);
seqstack.push(1);
seqstack.push(2);
seqstack.push(3);
console.writeline(seqstack);
console.writeline(seqstack.peek());
console.writeline(seqstack);
console.writeline(seqstack.pop());
console.writeline(seqstack);
console.writeline("链堆栈测试开始...");
linkstack<int> linkstack = new linkstack<int>();
linkstack.push(1);
linkstack.push(2);
linkstack.push(3);
console.writeline(linkstack);
console.writeline(linkstack.peek());
console.writeline(linkstack);
console.writeline(linkstack.pop());
console.writeline(linkstack);
console.readline();

注： .net中system.collections.generic.stack<t>已经提供了堆栈的基本实现，明白原理后，仍然推荐大家使用内置的实现。

希望本文所述对大家c#程序设计有所帮助。