詳解python數據結構之棧stack

前言

棧(Stack)是一種運算受限的線性表。

按照先進後出(FILO,First In Last Out)的原則存儲數據,先進入的數據被壓入棧底,最後的數據在棧頂。棧隻能在一端進行插入和刪除操作。

文章內容包含:

(1)棧的基本格式
(2)壓棧 push_stack
(3)出棧 pop_stack
(4)取棧頂 peek_stack

一、棧的基本格式

class Stack():
    def __init__ (self,size):
        self.size = size #棧空間大小
        self.top = -1 #棧中進入一個數據 top 加 1
        self.stack = [] 

    def display_stack(self):#棧stack的打印
        print(self.stack)

if __name__ == "__main__":
    stack = Stack(5) #設定棧空間
    stack.display_stack() #打印棧數據

二、進棧與壓棧 push_stack

class Stack():
    def __init__ (self,size):
        self.size = size
        self.top = -1
        self.stack = [] #進棧數據列表
    def display_stack(self):
        print(self.stack)
        
    def push_stack(self,data):
        if len(self.stack ) >= self.size: #當數據數量大於設置的空間,則棧溢出
            print("stack over flow!")
            return
        self.stack.append(data) #沒有棧溢出就將數據追加到列表中
        self.top += 1 #棧中每增加一個數據就加 1
        
if __name__ == "__main__":
    stack = Stack(5)
    stack.push_stack(0)
    stack.push_stack(1)
    stack.push_stack(2)
    stack.push_stack(3)
    stack.push_stack(4)
    stack.push_stack(5) #stack空間是 5,這裡進棧數據時 6 個,即提示棧溢出stack over flow!
    stack.display_stack()

執行結果:

在這裡插入圖片描述

三、出棧 pop_stack

class Stack():
    def __init__ (self,size):
        self.size = size
        self.top = -1
        self.stack = [] #進棧數據列表
    def display_stack(self):
        print(self.stack)   
    def push_stack(self,data):
        if len(self.stack ) >= self.size: 
            print("stack over flow!")
            return
        self.stack.append(data)
        self.top += 1 
	
	def pop_stack(self):
        if self.top <= -1: #當top小於等於初始值 -1 時說明stack數據列表為空
            print("stack is empty!")
            return
        ret = self.stack.pop() #stack數據列表不為空就取出最後進的值,列表數據數量就少一個
        self.top -= 1 
        return ret
        
if __name__ == "__main__":
    stack = Stack(5)
    stack.push_stack(0)
    stack.push_stack(1)
    stack.push_stack(2)
    stack.push_stack(3)
    stack.push_stack(4)
    stack.display_stack()
    #進棧數據有 5 個,出棧函數調用瞭 6 次,就出現瞭提示stack is empty!
    ret = stack.pop_stack()
    print(ret)
    stack.display_stack()
    ret = stack.pop_stack()
    print(ret)
    stack.display_stack()
    ret = stack.pop_stack()
    print(ret)
    stack.display_stack()
    ret = stack.pop_stack()
    print(ret)
    stack.display_stack()
    ret = stack.pop_stack()
    print(ret)
    stack.display_stack()
    ret = stack.pop_stack()
    print(ret)
    stack.display_stack()

執行結果:

在這裡插入圖片描述

四、取棧頂 peek_stack

class Stack():
    def __init__ (self,size):
        self.size = size
        self.top = -1
        self.stack = [] 
    def display_stack(self):
        print(self.stack)   
    def push_stack(self,data):
        if len(self.stack ) >= self.size: 
            print("stack over flow!")
            return
        self.stack.append(data) 
        self.top += 1 

	def peek_stack(self):
        if self.top == -1: #當棧內沒有數據時 提示 stack is empty!
            print("stack is empty!")
            return
        peek = self.stack[self.top] #棧不為空時,將棧頂的數據提取出來
        return peek
        
if __name__ == "__main__":
    stack = Stack(5)
    stack.push_stack(0)
    stack.push_stack(1)
    stack.push_stack(2)
    stack.push_stack(3)
    stack.push_stack(4)
    stack.push_stack(5) 
    stack.display_stack()
    peek = stack.peek_stack()
    print(peek)

執行結果:

在這裡插入圖片描述

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