代码随想录算法训练营第10天|232.用栈实现队列 225. 用队列实现栈

最新推荐文章于 2025-12-02 19:18:07 发布

原创最新推荐文章于 2025-12-02 19:18:07 发布 · 88 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#数据结构 #python #开发语言

文章介绍了如何使用栈实现队列以及用队列实现栈的Python代码，通过LeetCode上的相关问题展示了具体实现方法，强调了对内置函数的熟练运用在编程中的重要性。

理论基础

文章讲解：代码随想录

232.用栈实现队列

题目链接：LeetCode - The World's Leading Online Programming Learning Platform

题目链接/文章讲解/视频讲解：代码随想录

class MyQueue(object):

    def __init__(self):
        #set up two stack one for in and one for out
        self.stack_in=[]
        self.stack_out=[]
        

    def push(self, x):
        """
        :type x: int
        :rtype: None
        """
        #append new value to stack_in
        self.stack_in.append(x)

    def pop(self):
        """
        :rtype: int
        """
        #return none if empty. 
        if self.empty():
            return None
        #if there is element in stack_out, reomove and print the last element. 
        if self.stack_out:
            return self.stack_out.pop()
        #if there is no element in stack_out, move stack_in elements to
        #stack_out, then remove and print the last element. 
        else:
            for i in range(len(self.stack_in)-1,-1,-1):
                self.stack_out.append(self.stack_in[i])
            self.stack_in=[]
            return self.stack_out.pop()    

    def peek(self):
        """
        :rtype: int
        """
        #return none if empty.
        if self.empty():
            return None
        #if there is element in stack_out, print the last element.
        if self.stack_out:
            return self.stack_out[-1]
        #if there is no element in stack_out, move stack_in elements to
        #stack_out, then print the last element. 
        else:
            for i in range(len(self.stack_in)-1,-1,-1):
                self.stack_out.append(self.stack_in[i])
            self.stack_in=[]
            return self.stack_out[-1]    

    def empty(self):
        """
        :rtype: bool
        """
        #if there is element in stack_in or stack_out, our boolean should be 
        #False
        return not (self.stack_in or self.stack_out)

225. 用队列实现栈

题目链接：LeetCode - The World's Leading Online Programming Learning Platform

题目链接/文章讲解/视频讲解：代码随想录

from collections import deque
class MyStack(object):

    def __init__(self):
        #set up two queue
        self.queue_in=deque()
        self.queue_out=deque()

    def push(self, x):
        """
        :type x: int
        :rtype: None
        """
        #append to queue_in
        self.queue_in.append(x)
        

    def pop(self):
        """
        :rtype: int
        """
        #return none if empty
        if self.empty():
            return None
        #move all element except the last one to the other queue 
        #pop the last one 
        for i in range(len(self.queue_in)-1):
            self.queue_out.append(self.queue_in.popleft())
        self.queue_out,self.queue_in=self.queue_in,self.queue_out
        return self.queue_out.popleft()

    def top(self):
        """
        :rtype: int
        """
        #return none if empty
        if self.empty():
            return None
        #return the last one in the queue_in
        return self.queue_in[-1]

    def empty(self):
        """
        :rtype: bool
        """
        #check if there is element in queue_in
        return not(self.queue_in)

总结：

对于buildin function不够熟悉要多多运用