Update shortest-palindrome.py

Author: kamyu104

Diff for: Python/shortest-palindrome.py

@@ -22,8 +22,10 @@ def shortestPalindrome(self, s):
 
         A = s + s[::-1]
         prefix = self.getPrefix(A)
-            
-        return s[prefix[-1]+1:][::-1] + s
+        i = prefix[-1]
+        while i > len(s) - 1:
+            i = prefix[i]
+        return s[i+1:][::-1] + s
 
     def getPrefix(self, pattern):
         prefix = [-1] * len(pattern)