介紹
數據結構在計算機中組織存儲，以便我們可以有效地訪問和更改數據。 堆棧和隊列是計算機科學中定義的最早的數據結構。
堆棧
遵循后進先出 (Last-in-First-Out LIFO)原則。
- push - 在堆棧頂部添加元素：
- pop - 刪除堆棧頂部的元素：
隊列
遵循先入先出(FIFO:First-in-First-Out)原則。
- enqueue - 在隊列的開頭添加元素：
- dequeue - 刪除隊列開頭的元素：
使用列表實現堆棧和隊列
Python的內置List數據結構--------堆棧和隊列。
堆棧：
letters = [] # Let's push some letters into our list letters.append('c') letters.append('a') letters.append('t') letters.append('g') # Now let's pop letters, we should get 'g' last_item = letters.pop() print(last_item) # If we pop again we'll get 't' last_item = letters.pop() print(last_item) # 'c' and 'a' remain print(letters) # ['c', 'a']
執行結果：
g t ['c', 'a']
隊列：
fruits = [] # Let's enqueue some fruits into our list fruits.append('banana') fruits.append('grapes') fruits.append('mango') fruits.append('orange') # Now let's dequeue our fruits, we should get 'banana' first_item = fruits.pop(0) print(first_item) # If we dequeue again we'll get 'grapes' first_item = fruits.pop(0) print(first_item) # 'mango' and 'orange' remain print(fruits) # ['c', 'a']
執行結果
banana grapes ['mango', 'orange']
使用Deque庫的堆棧和隊列
deque是Double Ended Queue的縮寫 - 可以獲取存儲的第一個或最后一個元素的通用隊列，下面使用Deque庫的堆棧和隊列：
from collections import deque # you can initialize a deque with a list numbers = deque() # Use append like before to add elements numbers.append(99) numbers.append(15) numbers.append(82) numbers.append(50) numbers.append(47) # You can pop like a stack last_item = numbers.pop() print(last_item) # 47 print(numbers) # deque([99, 15, 82, 50]) # You can dequeue like a queue first_item = numbers.popleft() print(first_item) # 99 print(numbers) # deque([15, 82, 50])
執行結果
47 deque([99, 15, 82, 50]) 99 deque([15, 82, 50])
更嚴格的實現
創建撤消功能 - 允許用戶回溯他們的操作，直到會話開始。堆棧是這種情況的理想選擇。 我們可以通過將其推送到堆棧來記錄用戶所采取的每個操作。 當用戶想要撤消操作時，他們將從堆棧中彈出它。
游戲中，每次按下按鈕，都會觸發輸入事件。 測試人員注意到，如果按鈕按下得太快，游戲只處理第一個按鈕，特殊動作將無效！可以使用隊列修復它。 我們可以將所有輸入事件排入隊列。
#!/usr/bin/python3 # -*- coding: utf-8 -*- # 項目實戰討論QQ群630011153 144081101 # python測試開發庫匯總: https://github.com/china-testing/python-api-tesing/ # 本文最佳板式地址： https://www.jianshu.com/p/c990427ca608 # A simple class stack that only allows pop and push operations class Stack: def __init__(self): self.stack = [] def pop(self): if len(self.stack) < 1: return None return self.stack.pop() def push(self, item): self.stack.append(item) def size(self): return len(self.stack) # And a queue that only has enqueue and dequeue operations class Queue: def __init__(self): self.queue = [] def enqueue(self, item): self.queue.append(item) def dequeue(self): if len(self.queue) < 1: return None return self.queue.pop(0) def size(self): return len(self.queue) document_actions = Stack() # The first enters the title of the document document_actions.push('action: enter; text_id: 1; text: This is my favourite document') # Next they center the text document_actions.push('action: format; text_id: 1; alignment: center') # As with most writers, the user is unhappy with the first draft and undoes the center alignment document_actions.pop() # The title is better on the left with bold font document_actions.push('action: format; text_id: 1; style: bold') input_queue = Queue() # The player wants to get the upper hand so pressing the right combination of buttons quickly input_queue.enqueue('DOWN') input_queue.enqueue('RIGHT') input_queue.enqueue('B') # Now we can process each item in the queue by dequeueing them key_pressed = input_queue.dequeue() # 'DOWN' # We'll probably change our player position key_pressed = input_queue.dequeue() # 'RIGHT' # We'll change the player's position again and keep track of a potential special move to perform key_pressed = input_queue.dequeue() # 'B' # This can do the act, but the game's logic will know to do the special move