From 597f24d2a07341d2dadcc1ecbfdbff372863377c Mon Sep 17 00:00:00 2001
From: boom-jumper <56831966+boom-jumper@users.noreply.github.com>
Date: Thu, 27 May 2021 20:30:37 +0800
Subject: [PATCH 1/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A00232=E7=94=A8=E6=A0=88?=
 =?UTF-8?q?=E5=AE=9E=E7=8E=B0=E9=98=9F=E5=88=97=20python3=20=E7=89=88?=
 =?UTF-8?q?=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0232.用栈实现队列.md | 44 +++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/problems/0232.用栈实现队列.md b/problems/0232.用栈实现队列.md
index 10314a08..c2af71f7 100644
--- a/problems/0232.用栈实现队列.md
+++ b/problems/0232.用栈实现队列.md
@@ -282,6 +282,50 @@ 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.
+        """
+        self.stack1 = list()
+        self.stack2 = list()
+
+    def push(self, x: int) -> None:
+        """
+        Push element x to the back of queue.
+        """
+        # self.stack1用于接受元素
+        self.stack1.append(x)
+
+    def pop(self) -> int:
+        """
+        Removes the element from in front of queue and returns that element.
+        """
+        # 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()
+
+    def peek(self) -> int:
+        """
+        Get the front element.
+        """
+        if self.stack2 == []:
+            while self.stack1:
+                tmp = self.stack1.pop()
+                self.stack2.append(tmp)
+        return self.stack2[-1]
+
+    def empty(self) -> bool:
+        """
+        Returns whether the queue is empty.
+        """
+        return self.stack1 == [] and self.stack2 == []
+```
 
 
 Go：

From 0ae9d1808cf4db850f28ad9cfa837506bfec9588 Mon Sep 17 00:00:00 2001
From: boom-jumper <56831966+boom-jumper@users.noreply.github.com>
Date: Thu, 27 May 2021 20:37:53 +0800
Subject: [PATCH 2/2] =?UTF-8?q?=E6=B7=BB=E5=8A=A00150=E9=80=86=E6=B3=A2?=
 =?UTF-8?q?=E5=85=B0=E8=A1=A8=E8=BE=BE=E5=BC=8F=E6=B1=82=E5=80=BC=20python?=
 =?UTF-8?q?3=20=E7=89=88=E6=9C=AC?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0150.逆波兰表达式求值.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/problems/0150.逆波兰表达式求值.md b/problems/0150.逆波兰表达式求值.md
index e38bc1a3..c8b0da08 100644
--- a/problems/0150.逆波兰表达式求值.md
+++ b/problems/0150.逆波兰表达式求值.md
@@ -224,6 +224,22 @@ var evalRPN = function(tokens) {
 };
 ```
 
+python3
+
+```python
+def evalRPN(tokens) -> int:
+    stack = list()
+    for i in range(len(tokens)):
+        if tokens[i] not in ["+", "-", "*", "/"]:
+            stack.append(tokens[i])
+        else:
+            tmp1 = stack.pop()
+            tmp2 = stack.pop()
+            res = eval(tmp2+tokens[i]+tmp1)
+            stack.append(str(int(res)))
+    return stack[-1]
+```
+
 
 -----------------------
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)