Update 012._Integer_to_Roman.md

012._Integer_to_Roman.md

@@ -64,22 +64,35 @@ via <http://www.cnblogs.com/cacique/archive/2012/02/23/2364377.html>
 
 AC代码
 
-```
-
+```python
 class Solution(object):
     def intToRoman(self, num):
         """
         :type num: int
         :rtype: str
         """
-        lookup = {'M':1000, 'CM':900, 'D':500, 'CD':400, 'C':100, 'XC':90, 'L':50, 'XL':40, 'X':10, 'IX':9, 'V':5, 'IV':4, 'I':1}
-        romanSt = ''
+        lookup = {
+            'M': 1000, 
+            'CM': 900, 
+            'D': 500, 
+            'CD': 400, 
+            'C': 100, 
+            'XC': 90, 
+            'L': 50, 
+            'XL': 40, 
+            'X': 10, 
+            'IX': 9, 
+            'V': 5, 
+            'IV': 4, 
+            'I': 1
+        }
+        romanStr = ''
 
         for symbol, val in sorted(lookup.items(), key = lambda t: t[1], reverse = True):
         	while num >= val:
-        		romanSt += symbol
+        		romanStr += symbol
         		num -= val
-        return romanSt
+        return romanStr
 ```