LiamHuang: 解决第二题

Liam0205 · Liam0205 · commit c065ddf16eca · 2015-05-07T21:37:49.000+08:00
笔记参见： http://liam0205.me/2015/05/07/generator-of-invitation-code-in-python/
diff --git a/LiamHuang/0000/solution.py b/LiamHuang/0000/solution.py
@@ -3,6 +3,10 @@
 0000：
 将你的 QQ 头像（或者微博头像）右上角加上红色的数字，类似于微信未读信息数量那种提示效果。
 类似于图中效果 http://i.imgur.com/sg2dkuY.png?1
+
+笔记参见：
+http://liam0205.me/2015/04/22/pil-tutorial-basic-usage/
+http://liam0205.me/2015/05/05/pil-tutorial-imagedraw-and-imagefont/
 """
 
 from PIL import Image, ImageDraw, ImageFont
diff --git a/LiamHuang/0001/solution.py b/LiamHuang/0001/solution.py
@@ -0,0 +1,47 @@
+# coding: utf-8
+
+'''
+做为 Apple Store App 独立开发者，你要搞限时促销，为你的应用生成激活码（或者优惠券），
+使用 Python 如何生成 200 个激活码（或者优惠券）？
+'''
+
+import random, string
+
+class LengthError(ValueError):
+   def __init__(self, arg):
+      self.args = arg
+
+def pad_zero_to_left(inputNumString, totalLength):
+    '''
+    takes inputNumString as input,
+    pads zero to its left, and make it has the length totalLength
+    1. calculates the length of inputNumString
+    2. compares the length and totalLength
+        2.1 if length > totalLength, raise an error
+        2.2 if length == totalLength, return directly
+        2.3 if length < totalLength, pads zeros to its left
+    '''
+    lengthOfInput = len(inputNumString)
+    if lengthOfInput > totalLength:
+        raise LengthError("The length of input is greater than the total\ length.")
+    else:
+        return '0' * (totalLength - lengthOfInput) + inputNumString
+
+poolOfChars = string.ascii_letters + string.digits
+random_codes = lambda x, y: ''.join([random.choice(x) for i in range(y)])
+
+def invitation_code_generator(quantity, lengthOfRandom, LengthOfKey):
+    '''
+    generate `quantity` invitation codes
+    '''
+    placeHoldChar = "L"
+    for index in range(quantity):
+        tempString = ""
+        try:
+            yield random_codes(poolOfChars, lengthOfRandom) + placeHoldChar + \
+                pad_zero_to_left(str(index), LengthOfKey)
+        except LengthError:
+            print "Index exceeds the length of master key."
+
+for invitationCode in invitation_code_generator(200, 16, 4):
+    print invitationCode
