reorganize dir

Signed-off-by: Mia Steinkirch <mia.steinkirch@gmail.com>

ebook_src/real_interview_problems/reverse_str.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+def reverse_str_inplace(_str):
+    if len(_str) < 2:
+        return _str
+    return _str[-1] + reverse_str(_str[1:-1]) + _str[0]
+    
+
+def reverse_str(_str):
+    result = ''
+    j = len(_str) - 1
+
+    while j >= 0:
+        result += _str[j]
+    
+    return result
+    
+    
+if __name__ == '__main__':
+    _str = ''
+    result = ''
+    assert(reverse_str(_str) == result)
+    assert(reverse_str_inplace(_str) == result)
+
+    _str = 'a'
+    result = 'a'
+    assert(reverse_str(_str) == result)
+    assert(reverse_str_inplace(_str) == result)
+
+    _str = 'abcde'
+    result = 'edcba'
+    assert(reverse_str(_str) == result)
+    assert(reverse_str_inplace(_str) == result)
+
+    _str = 'abcdef'
+    result = 'fedcba'
+    assert(reverse_str(_str) == result)
+    assert(reverse_str_inplace(_str) == result)