数据结构C#版笔记--堆栈(Stack)
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。
相对前面学习过的顺序表、链表不同的地方在于：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:
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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：
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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
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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
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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：
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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(); |
.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。
作者：菩提树下的杨过
出处：http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。
出处：http://yjmyzz.cnblogs.com
本文版权归作者和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。