1 files changed, 49 insertions, 0 deletions
diff --git a/challenge-190/roger-bell-west/python/ch-2.py b/challenge-190/roger-bell-west/python/ch-2.py
new file mode 100755
index 0000000000..9114d511ba
--- /dev/null
+++ b/challenge-190/roger-bell-west/python/ch-2.py
@@ -0,0 +1,49 @@
+#! /usr/bin/python3
+
+import unittest
+
+from collections import deque
+
+def decodedlist(s):
+  stack = deque()
+  stack.append([s])
+  out = set()
+  while True:
+    ent = stack.popleft()
+    tail = ent.pop()
+    if len(tail) == 0:
+      out.add(tuple(ent))
+    else:
+      if tail[0] != "0":
+        q = ent.copy()
+        q.append(tail[0])
+        q.append(tail[1:])
+        stack.append(q)
+      if len(tail) >= 2:
+        v = int(tail[0:2])
+        if v >= 1 and v <= 26:
+          q = ent.copy()
+          q.append(tail[0:2])
+          q.append(tail[2:])
+          stack.append(q)
+    if len(stack) == 0:
+      break
+  k = []
+  alphazero = ord("A") - 1
+  for x in out:
+    k.append("".join(chr(int(cs)+alphazero) for cs in x))
+  k.sort()
+  return k
+
+class TestDecodecounts(unittest.TestCase):
+            
+  def test_ex1(self):
+    self.assertEqual(decodedlist("11"), ["AA", "K"], 'example 1')
+
+  def test_ex2(self):
+    self.assertEqual(decodedlist("1115"), ["AAAE", "AAO", "AKE", "KAE", "KO"], 'example 2')
+
+  def test_ex3(self):
+    self.assertEqual(decodedlist("127"), ["ABG", "LG"], 'example 3')
+
+unittest.main()