1 files changed, 28 insertions, 0 deletions
diff --git a/challenge-263/steven-wilson/python/ch-2.py b/challenge-263/steven-wilson/python/ch-2.py
new file mode 100644
index 0000000000..40895fcd98
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+++ b/challenge-263/steven-wilson/python/ch-2.py
@@ -0,0 +1,28 @@
+#!/usr/bin/env python3
+
+from collections import Counter
+
+
+def merge_items(items1, items2):
+    ''' Given two 2-D array of positive integers, items1 and items2 where
+    element is pair of (item_id, item_quantity), return the merged items.
+    >>> merge_items([ [1,1], [2,1], [3,2] ], [ [2,2], [1,3] ])
+    [[1, 4], [2, 3], [3, 2]]
+    >>> merge_items([[1, 2], [2, 3], [1, 3], [3, 2]], [[3, 1], [1, 3]])
+    [[1, 8], [2, 3], [3, 3]]
+    >>> merge_items([[1, 1], [2, 2], [3, 3]], [[2, 3], [2, 4]])
+    [[1, 1], [2, 9], [3, 3]]
+    '''
+    counter = Counter()
+    all_items = items1 + items2
+
+    for item in all_items:
+        counter[item[0]] += item[1]
+
+    return [[item_id, counter[item_id]] for item_id in sorted(counter.keys())]
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()