Create smallest-common-region.py

Python/smallest-common-region.py

@@ -0,0 +1,21 @@
+# Time:  O(m * n)
+# Space: O(n)
+
+class Solution(object):
+    def findSmallestRegion(self, regions, region1, region2):
+        """
+        :type regions: List[List[str]]
+        :type region1: str
+        :type region2: str
+        :rtype: str
+        """
+        parents = {region[i] : region[0]
+                   for region in regions
+                   for i in xrange(1, len(region))}
+        lookup = {region1}
+        while region1 in parents:
+            region1 = parents[region1]
+            lookup.add(region1)
+        while region2 not in lookup:
+            region2 = parents[region2]
+        return region2