栈
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今天跟大家聊聊栈,在程序设计中,栈的使用还是非常广泛的,比如有“括号匹配问题“,”html结构匹配问题“。
所以说掌握了”栈“的使用,对我们学习算法还是很有帮助的。
一: 概念
栈,同样是一种特殊的线性表,是一种Last In First Out(LIFO)的形式,现实中有很多这样的例子,
比如:食堂中的一叠盘子,我们只能从顶端一个一个的取。
二:存储结构
”栈“不像”队列“,需要两个指针来维护,栈只需要一个指针就够了,这得益于栈是一种一端受限的线性表。
这里同样用”顺序结构“来存储这个”栈“,top指针指向栈顶,所有的操作只能在top处。
代码段:
1 #region 栈的数据结构 2 /// <summary> 3 /// 栈的数据结构 4 /// </summary> 5 public class SeqStack<T> 6 { 7 public T[] data; 8 9 /// <summary>10 /// 栈顶指针11 /// </summary>12 public int top = -1;13 14 public SeqStack(int lenth)15 {16 data = new T[lenth];17 }18 }19 #endregion
三:常用操作
栈的操作有:①初始化栈,②入栈,③出栈,④获取栈顶。
1: 初始化栈
这个还是比较简单的,初始化栈时,设置默认top指针为-1,这个就不用图来展示了。
代码段:
1 #region 栈的初始化操作 2 /// <summary> 3 /// 栈的初始化操作 4 /// </summary> 5 /// <typeparam name="T"></typeparam> 6 /// <returns></returns> 7 public SeqStack<T> SeqStackInit<T>(int length) 8 { 9 SeqStack<T> seqStack = new SeqStack<T>(length);10 11 seqStack.top = -1;12 13 return seqStack;14 }15 #endregion
2:入栈
这个操作主要就是做两件事情:① 将元素从栈顶压入,② top指针自增。
代码段:
1 #region 入栈 2 /// <summary> 3 /// 入栈 4 /// </summary> 5 /// <typeparam name="T"></typeparam> 6 /// <param name="seqStack"></param> 7 /// <param name="data"></param> 8 public void SeqStackPush<T>(SeqStack<T> seqStack, T data) 9 {10 if (SeqStackIsFull(seqStack))11 throw new Exception("不好意思,栈溢出");12 13 seqStack.data[++seqStack.top] = data;14 }15 #endregion
3:出栈
同样跟“入栈”类似,需要做两件事情,①干掉top处的元素,②top指针自减。
代码段
1 #region 出栈 2 /// <summary> 3 /// 出栈 4 /// </summary> 5 /// <typeparam name="T"></typeparam> 6 /// <param name="seqStack"></param> 7 /// <returns></returns> 8 public T SeqStackPop<T>(SeqStack<T> seqStack) 9 {10 if (SeqStackIsEmpty(seqStack))11 throw new Exception("呜呜,栈已空");12 13 seqStack.data[seqStack.top] = default(T);14 15 return seqStack.data[--seqStack.top];16 }17 #endregion
4:获取栈顶元素
这个很简单,跟“出栈”唯一不同的是不破坏栈顶元素,只是翻出来看看而已。
代码段
1 #region 获取栈顶 2 /// <summary> 3 /// 获取栈顶 4 /// </summary> 5 /// <typeparam name="T"></typeparam> 6 /// <param name="seqStack"></param> 7 /// <returns></returns> 8 public T SeqStackPeek<T>(SeqStack<T> seqStack) 9 {10 if (SeqStackIsEmpty(seqStack))11 throw new Exception("栈已空");12 13 return seqStack.data[seqStack.top];14 }15 #endregion
总的运行代码如下
View Code
1 using System; 2 using System.Collections.Generic; 3 using System.Linq; 4 using System.Text; 5 6 namespace SeqStack 7 { 8 class Program 9 { 10 static void Main(string[] args) 11 { 12 SeqStackClass stackManager = new SeqStackClass(); 13 14 SeqStack<Student> seqStack = stackManager.SeqStackInit<Student>(10); 15 16 Console.WriteLine("******************** 压入ID=1,ID=2,ID=3的元素 ***********************\n"); 17 //压入ID=1,ID=2,ID=3的元素 18 stackManager.SeqStackPush(seqStack, new Student() { ID = 1, Name = "一线码农", Age = 23 }); 19 stackManager.SeqStackPush(seqStack, new Student() { ID = 2, Name = "huangxincheng520", Age = 23 }); 20 stackManager.SeqStackPush(seqStack, new Student() { ID = 3, Name = "51cto", Age = 23 }); 21 22 Console.WriteLine(".... 压入成功,当前栈中元素有:" + stackManager.SeqStackLen(seqStack) + "个"); 23 24 Console.WriteLine("\n****************** 查看栈顶元素 ********************"); 25 26 var result = stackManager.SeqStackPeek(seqStack); 27 28 Console.WriteLine("栈顶元素为:ID=" + result.ID + ",Name=" + result.Name + ",Age=" + result.Age); 29 30 Console.WriteLine("\n******************** 弹出栈顶元素 ***********************"); 31 32 stackManager.SeqStackPop(seqStack); 33 34 Console.WriteLine("\n****************** 查看栈中的元素 ********************"); 35 36 for (int i = 0; i < stackManager.SeqStackLen(seqStack); i++) 37 { 38 Console.WriteLine("栈顶元素为:ID=" + seqStack.data[i].ID + ",Name=" + seqStack.data[i].Name + ",Age=" + seqStack.data[i].Age); 39 } 40 41 Console.Read(); 42 } 43 } 44 45 #region 学生数据实体 46 /// <summary> 47 /// 学生数据实体 48 /// </summary> 49 public class Student 50 { 51 public int ID { get; set; } 52 53 public string Name { get; set; } 54 55 public int Age { get; set; } 56 } 57 #endregion 58 59 #region 栈的数据结构 60 /// <summary> 61 /// 栈的数据结构 62 /// </summary> 63 public class SeqStack<T> 64 { 65 public T[] data; 66 67 /// <summary> 68 /// 栈顶指针 69 /// </summary> 70 public int top = -1; 71 72 public SeqStack(int lenth) 73 { 74 data = new T[lenth]; 75 } 76 } 77 #endregion 78 79 public class SeqStackClass 80 { 81 #region 栈的初始化操作 82 /// <summary> 83 /// 栈的初始化操作 84 /// </summary> 85 /// <typeparam name="T"></typeparam> 86 /// <returns></returns> 87 public SeqStack<T> SeqStackInit<T>(int length) 88 { 89 SeqStack<T> seqStack = new SeqStack<T>(length); 90 91 seqStack.top = -1; 92 93 return seqStack; 94 } 95 #endregion 96 97 #region 判断栈是否为空 98 /// <summary> 99 /// 判断栈是否为空100 /// </summary>101 /// <typeparam name="T"></typeparam>102 /// <param name="seqStack"></param>103 /// <returns></returns>104 public bool SeqStackIsEmpty<T>(SeqStack<T> seqStack)105 {106 return seqStack.top == -1;107 }108 #endregion109 110 #region 清空栈111 /// <summary>112 /// 清空栈113 /// </summary>114 /// <typeparam name="T"></typeparam>115 /// <param name="seqStack"></param>116 public void SeqStackClear<T>(SeqStack<T> seqStack)117 {118 seqStack.top = -1;119 }120 #endregion121 122 #region 栈是否已满123 /// <summary>124 /// 栈是否已满125 /// </summary>126 /// <typeparam name="T"></typeparam>127 /// <param name="seqStack"></param>128 public bool SeqStackIsFull<T>(SeqStack<T> seqStack)129 {130 return seqStack.top == seqStack.data.Length;131 }132 #endregion133 134 #region 入栈135 /// <summary>136 /// 入栈137 /// </summary>138 /// <typeparam name="T"></typeparam>139 /// <param name="seqStack"></param>140 /// <param name="data"></param>141 public void SeqStackPush<T>(SeqStack<T> seqStack, T data)142 {143 if (SeqStackIsFull(seqStack))144 throw new Exception("不好意思,栈溢出");145 146 seqStack.data[++seqStack.top] = data;147 }148 #endregion149 150 #region 出栈151 /// <summary>152 /// 出栈153 /// </summary>154 /// <typeparam name="T"></typeparam>155 /// <param name="seqStack"></param>156 /// <returns></returns>157 public T SeqStackPop<T>(SeqStack<T> seqStack)158 {159 if (SeqStackIsEmpty(seqStack))160 throw new Exception("呜呜,栈已空");161 162 seqStack.data[seqStack.top] = default(T);163 164 return seqStack.data[--seqStack.top];165 }166 #endregion167 168 #region 获取栈顶169 /// <summary>170 /// 获取栈顶171 /// </summary>172 /// <typeparam name="T"></typeparam>173 /// <param name="seqStack"></param>174 /// <returns></returns>175 public T SeqStackPeek<T>(SeqStack<T> seqStack)176 {177 if (SeqStackIsEmpty(seqStack))178 throw new Exception("栈已空");179 180 return seqStack.data[seqStack.top];181 }182 #endregion183 184 #region 获取栈中元素个数185 /// <summary>186 /// 获取栈中元素个数187 /// </summary>188 /// <typeparam name="T"></typeparam>189 /// <param name="seqStack"></param>190 /// <returns></returns>191 public int SeqStackLen<T>(SeqStack<T> seqStack)192 {193 return seqStack.top + 1;194 }195 #endregion196 }197 }
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