Question

我有一些堆栈代码，如下所示：

class Stack():

  def init(self):
    self.items = []

  def isEmpty(self):
    return self.items == []

  def push(self, item):
    return self.items.append(item)

  def pop(self):
    return self.items.pop()

  def getElements(self):
    return self.items

队列的等价物是什么？

Answer 1

队列是先入先出，这很容易实现。

class Stack:
    def __init__(self):
        self.items = []

    def is_empty(self):
        return self.items == []

    def push(self, item):
        return self.items.append(item)

    def pop(self):
        return self.items.pop()

    def get_elements(self):
        return self.items

class Queue:
    def __init__(self):
        self.items = []

    def is_empty(self):
        return self.items == []

    def push(self, item):
        return self.items.append(item)

    def pull(self):
        return self.items.pop(0)

    def get_elements(self):
        return self.items

stack = Stack() # items = []
stack.push("A") # items = ["A"]
stack.push("B") # items = ["A", "B"]
stack.push("C") # items = ["A", "B", "C"]
stack.pop() # items = ["A", "B"]

queue = Queue() # items = []
queue.push("A") # items = ["A"]
queue.push("B") # items = ["A", "B"]
queue.push("C") # items = ["A", "B", "C"]
queue.pull() #items = ["B", "C"]

Answer 2

不要像Java一样使用Python，为这些基本ADT定义类不是“Pythonic”，更不用说由于额外的包装而违背性能。

内置列表可以做到这一点以及更多。

堆栈是LIFO（后进先出）

Using Lists as Stacks

>>> stack = []

# push, use append
>>> stack.append(1)
>>> stack.append(2)
>>> stack.append(3)

# pop
>>> stack.pop() # to get the last inserted element
>>>
3

# isEmpty
>>> if stack:
>>>     print('not empty')

队列是FIFO（先进先出）

Using Lists as Queues

>>> queue = collections.deque()

# push, use append
>>> queue.append(1)
>>> queue.append(2)
>>> queue.append(3)

# pull, use popleft to get the "first" inserted element
>>> queue.popleft()
>>>
1

Python中队列的定义是什么？

2 个答案: