one away solution python3

Author: nickolasteixeira

Python/chapter01/1.5 - OneAway/Nick.py

@@ -0,0 +1,42 @@
+#!/usr/bin/python3
+import unittest
+
+
+def one_away(s1, s2):
+    '''Given two strings, write a function to check if
+    they are one edit (or zero edits) away.'''
+    if abs(len(s1) - len(s2)) > 1:
+        return False
+
+    str1 = s1 if len(s1) < len(s2) else s2
+    str2 = s2 if len(s1) < len(s2) else s1
+    idx1, idx2 = 0, 0
+    diff = False
+
+    while idx1 < len(str1) and idx2 < len(str2):
+        if str1[idx1] is not str2[idx2]:
+            if diff:
+                return False
+            diff = True
+
+            if len(str1) is len(str2):
+                idx1 += 1
+        else:
+            idx1 += 1
+        idx2 += 1
+
+    return True
+
+
+class Test(unittest.TestCase):
+    def test1(self):
+        s1 = "Tact Cat"
+        s2 = "TactCat"
+        s3 = "nick"
+        s4 = "jeff"
+        self.assertTrue(one_away(s1, s2))
+        self.assertFalse(one_away(s3, s4))
+
+
+if __name__ == '__main__':
+    unittest.main()