add is isomorphic algorithm

dori-dev · dori-dev · commit b51515515c43 · 2022-08-03T08:58:12.000+04:30
diff --git a/strings/isomorphic.py b/strings/isomorphic.py
@@ -0,0 +1,28 @@
+"""
+is_isomorphic('foo', 'bar') => False
+is_isomorphic('foo', 'bee') => True
+complexity: O(n)
+"""
+
+
+def is_isomorphic(base_string: str, string: str) -> bool:
+    if len(base_string) != len(string):
+        return False
+    string_relations = {}
+    for base_letter, letter in zip(base_string, string):
+        correct_letter = string_relations.get(base_letter)
+        if letter in string_relations.values() and correct_letter is None:
+            return False
+        if correct_letter is None:
+            string_relations[base_letter] = letter
+            continue
+        if correct_letter != letter:
+            return False
+    return True
+
+
+if __name__ == "__main__":
+    print(is_isomorphic('foo', 'bar') is False)
+    print(is_isomorphic('foo', 'bee') is True)
+    print(is_isomorphic('fow', 'bee') is False)
+    print(is_isomorphic('paper', 'title') is True)
