From c6fb71c8f4d4bd164a00cffe5bbb0dcab691f8de Mon Sep 17 00:00:00 2001
From: Hui Lan <lanhui@zjnu.edu.cn>
Date: Mon, 22 Apr 2019 15:44:08 +0800
Subject: Removed import operator from the function sort_by_nth_element2 as it
 is not needed

---
 LectureNotesOnPython.rst | 81 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 79 insertions(+), 2 deletions(-)

diff --git a/LectureNotesOnPython.rst b/LectureNotesOnPython.rst
index de6e81e..8223567 100644
--- a/LectureNotesOnPython.rst
+++ b/LectureNotesOnPython.rst
@@ -1171,7 +1171,7 @@ key与value互换
 
 每个py文件就是一个模块。 每个模块有一个隐含的变量指示模块名， ``__name__`` 。
 
-当该py文件作为主模块运行时， ``__name__`` 的值是 ``__main__`` 。 当该py文件作为被引入的模块时，该模块的 ``__name__`` 的是模块名。
+当该py文件作为主模块运行时， ``__name__`` 的值是 ``__main__`` 。 当该py文件作为被引入的模块时，该模块的 ``__name__`` 的是模块名 （是文件名）。
 
 在每个py文件 ``if __name__ == '__main__':`` 后添加测试代码， 当这个py文件作为主模块运行时，测试代码会被执行。 而当引入这个py文件时，该文件的测试代码不会被执行，我们也不希望它们执行。
 
@@ -1375,7 +1375,6 @@ Python 自带的排序算法最快， ``selection_sort`` 最慢。
          
          def sort_by_nth_element2(lst, n):
              ''' Return a sorted list of tuples lst, according to the nth element in each tuple.'''
-             import operator
              result = sorted(lst, key=lambda x: x[n]) # https://stackoverflow.com/questions/8966538/syntax-behind-sortedkey-lambda
              return result
          
@@ -1455,6 +1454,84 @@ Python 自带的排序算法最快， ``selection_sort`` 最慢。
 
 
 
+递归
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Memo
+``````````````````````````````````````````````````
+
+.. code:: python
+
+         def fibonacci(n):
+             if n == 0:
+                 return 0
+             elif n == 1:
+                 return 1
+             else:
+                 return fibonacci(n-1) + fibonacci(n-2)
+         
+         
+         known = {0:0, 1:1}
+         def fibonacci_memo(n):
+             ''' A  'memoized' version of fibonacci. '''
+             if n in known:
+                 return known[n]
+             res = fibonacci(n-1) + fibonacci(n-2)
+             known[n] = res
+             return res
+         
+         
+         n = 35
+         import time
+         t1 = time.time()
+         print(fibonacci(n))
+         print('%4.2f' % (time.time() - t1))
+         
+         t1 = time.time()
+         print(fibonacci_memo(n))
+         print('%4.2f' % (time.time() - t1))
+         
+
+用递归方式改写 ``selection_sort``
+```````````````````````````````````````````````````
+
+.. code:: python
+	  
+         def selection_sort(L):
+             if len(L) <= 1:
+                 return L
+             
+             min_val = L[0]
+             k = j = 0
+             while j < len(L):
+                 if L[j] < min_val:
+                     min_val = L[j]
+                     k = j
+                 j += 1
+             L[k], L[0] = L[0], L[k]
+             return [min_val] + selection_sort(L[1:]) 
+         
+
+
+类 class 与 对象 object
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+
+web 应用程序
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+输入文本
+``````````````````````````````````````````````````
+
+school.py
+
+
+上传文件
+```````````````````````````````````````````````````
+
+omg
+
+	  
 参考
 ------
 
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