From a69006f901230b1ba73e73ce8b86918b404480e4 Mon Sep 17 00:00:00 2001
From: Eyjan_Huang <81480748+Eyjan-Huang@users.noreply.github.com>
Date: Fri, 20 Aug 2021 00:06:33 +0800
Subject: [PATCH] =?UTF-8?q?=E6=9B=B4=E6=96=B0=200232.=E7=94=A8=E6=A0=88?=
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python代码简化，符合PEP8标准，可读性加强，效率提升
---
 problems/0232.用栈实现队列.md | 50 ++++++++++++++++-------------
 1 file changed, 28 insertions(+), 22 deletions(-)

diff --git a/problems/0232.用栈实现队列.md b/problems/0232.用栈实现队列.md
index 0df82d35..46d884d3 100644
--- a/problems/0232.用栈实现队列.md
+++ b/problems/0232.用栈实现队列.md
@@ -281,48 +281,54 @@ class MyQueue {
 
 Python：
 ```python
-# 使用两个栈实现先进先出的队列
 class MyQueue:
+
     def __init__(self):
         """
-        Initialize your data structure here.
+        in主要负责push，out主要负责pop
         """
-        self.stack1 = list()
-        self.stack2 = list()
+        self.stack_in = []
+        self.stack_out = []
+
 
     def push(self, x: int) -> None:
         """
-        Push element x to the back of queue.
+        有新元素进来，就往in里面push
         """
-        # self.stack1用于接受元素
-        self.stack1.append(x)
+        self.stack_in.append(x)
+
 
     def pop(self) -> int:
         """
-        Removes the element from in front of queue and returns that element.
+        1. 检查如果out里面元素，则直接pop
+        2. 如果out没有元素，就把in里面的元素（除了第一个）依次pop后装进out里面
+        3. 直接把in剩下的元素pop出来，就是queue头部的
         """
-        # self.stack2用于弹出元素，如果self.stack2为[],则将self.stack1中元素全部弹出给self.stack2
-        if self.stack2 == []:
-            while self.stack1:
-                tmp = self.stack1.pop()
-                self.stack2.append(tmp)
-        return self.stack2.pop()
+        if self.stack_out:
+            return self.stack_out.pop()
+        else:
+            for i in range(1, len(self.stack_in)):
+                self.stack_out.append(self.stack_in.pop())
+            return self.stack_in.pop()
+
 
     def peek(self) -> int:
         """
-        Get the front element.
+        1. 查out有没有元素，有就把最上面的返回
+        2. 如果out没有元素，就把in最下面的返回
         """
-        if self.stack2 == []:
-            while self.stack1:
-                tmp = self.stack1.pop()
-                self.stack2.append(tmp)
-        return self.stack2[-1]
+        if self.stack_out:
+            return self.stack_out[-1]
+        else:
+            return self.stack_in[0]
+
 
     def empty(self) -> bool:
         """
-        Returns whether the queue is empty.
+        只要in或者out有元素，说明队列不为空
         """
-        return self.stack1 == [] and self.stack2 == []
+        return not (self.stack_in or self.stack_out)
+
 ```