Merge pull request youngyangyang04#218 from tw2665/patch-4

add python solution to 0541.reverseStrII

problems/0541.反转字符串II.md

@@ -134,6 +134,36 @@ class Solution {
 ```
 
 Python：
+```python
+
+class Solution(object):
+ def reverseStr(self, s, k):
+ """
+ :type s: str
+ :type k: int
+ :rtype: str
+ """
+ from functools import reduce
+ # turn s into a list 
+ s = list(s)
+
+ # another way to simply use a[::-1], but i feel this is easier to understand
+ def reverse(s):
+ left, right = 0, len(s) - 1
+ while left < right:
+ s[left], s[right] = s[right], s[left]
+ left += 1
+ right -= 1
+ return s
+
+ # make sure we reverse each 2k elements 
+ for i in range(0, len(s), 2*k):
+ s[i:(i+k)] = reverse(s[i:(i+k)])
+
+ # combine list into str.
+ return reduce(lambda a, b: a+b, s)
+
+```
 
 
 Go：