2 files changed, 63 insertions, 0 deletions
diff --git a/challenge-280/steven-wilson/python/ch-1.py b/challenge-280/steven-wilson/python/ch-1.py
new file mode 100644
index 0000000000..dc4c9d8dab
--- /dev/null
+++ b/challenge-280/steven-wilson/python/ch-1.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+from collections import Counter
+from string import ascii_lowercase
+
+
+def twice_appearance(string):
+    """ Given a string containing lowercase English letters only, return the
+    first letter that appears twice.
+
+    >>> twice_appearance("acbddbca")
+    'd'
+    >>> twice_appearance("abccd")
+    'c'
+    >>> twice_appearance("abcdabbb")
+    'a'
+    >>> twice_appearance("abcdefgh")
+
+    """
+    if any(c not in ascii_lowercase for c in string):
+        raise ValueError("String should contain only lowercase letters")
+
+    counter = Counter()
+    for c in string:
+        counter[c] += 1
+        if counter[c] == 2:
+            return c
+    return None
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod(verbose=True)
diff --git a/challenge-280/steven-wilson/python/ch-2.py b/challenge-280/steven-wilson/python/ch-2.py
new file mode 100644
index 0000000000..8a833439c0
--- /dev/null
+++ b/challenge-280/steven-wilson/python/ch-2.py
@@ -0,0 +1,29 @@
+#!/usr/bin/env python3
+
+
+def count_asterisks(string):
+    """ Given a string, where every two consecutive vertical bars are grouped
+    into a pair, return the number of asterisks, *, excluding any between each
+    pair of vertical bars.
+
+    >>> count_asterisks("p|*e*rl|w**e|*ekly|")
+    2
+    >>> count_asterisks("perl")
+    0
+    >>> count_asterisks("th|ewe|e**|k|l***ych|alleng|e")
+    5
+    """
+    between = False
+    asterisks = 0
+    for c in string:
+        if c == "|":
+            between = not between
+        if not between and c == "*":
+            asterisks += 1
+    return asterisks
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod(verbose=True)