completed 1.9

Author: sloloris

chapter-1-arrays-and-strings/1.9-string-rotation.py

@@ -1,7 +1,24 @@
 """ 1.9 String Rotation: Assume you have a method isSubstring which checks if one word is a substring of another. Given two strings, s1 and s2, write code to check if s2 is a rotation of s1 using only one call to isSubstring. """
 
+
 def is_rotation(s1, s2):
     """ Example inputs
 
         >>> is_rotation("waterbottle", "erbottlewat")
-        True
+        True
+    """
+    if len(s1) != len(s2) or len(s1) == 0:
+        return False
+
+    superstring = s1 + s1
+    return isSubstring(superstring, s2)
+
+
+# theoretically this should work, hard to test though
+
+
+    
+            
+
+
+