1 files changed, 34 insertions, 0 deletions
diff --git a/challenge-255/steven-wilson/python/ch-1.py b/challenge-255/steven-wilson/python/ch-1.py
new file mode 100644
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+++ b/challenge-255/steven-wilson/python/ch-1.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+from collections import Counter
+
+
+def odd_character(original, shuffled):
+    ''' Given two strings, the second string generated using the shuffled
+    characters of the first string with an additional character.  Function
+    returns the additional character.
+    >>> odd_character("Perl", "Preel")
+    'e'
+    >>> odd_character("Weekly", "Weeakly")
+    'a'
+    >>> odd_character("Box", "Boxy")
+    'y'
+    '''
+    if not original or not shuffled:
+        raise ValueError("Both strings must be non-empty.")
+
+    original_counter = Counter(original.casefold())
+    shuffled_counter = Counter(shuffled.casefold())
+
+    difference_counter = shuffled_counter - original_counter
+
+    if not difference_counter or sum(difference_counter.values()) > 1:
+        raise ValueError("No unique additional character found.")
+
+    return next(difference_counter.elements())
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()