D. J.:

- Added leetcode problem and solution for 205 Isomorphic Strings

Author: nobodyPerfecZ

README.md

@@ -15,6 +15,7 @@ This repository contains awesome LeetCode problems and solutions written in Pyth
 - [125 Valid Palindrome](https://leetcode.com/problems/valid-palindrome/description/)
 - [169 Majority Element](https://leetcode.com/problems/majority-element/description/)
 - [189 Rotate Array](https://leetcode.com/problems/rotate-array/description/)
+- [205 Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/description/)
 - [383 Ransom Note](https://leetcode.com/problems/ransom-note/description/)
 - [392 Is Subsequence](https://leetcode.com/problems/is-subsequence/description/)
 

awesome_python_leetcode/_205_isomorphic_strings.py

@@ -0,0 +1,21 @@
+class Solution:
+    def isIsomorphic(self, s: str, t: str) -> bool:
+        """
+        Given two strings s and t, determine if they are isomorphic.
+
+        Two strings s and t are isomorphic if the characters in s can be replaced to get t.
+
+        All occurrences of a character must be replaced with another character while preserving the order of characters.
+        No two characters may map to the same character, but a character may map to itself.
+        """
+        if len(s) != len(t):
+            return False
+        policy, reverse_policy = {}, {}
+        for s_, t_ in zip(s, t):
+            if s_ in policy and policy[s_] != t_:
+                return False
+            if t_ in reverse_policy and reverse_policy[t_] != s_:
+                return False
+            policy[s_] = t_
+            reverse_policy[t_] = s_
+        return True

tests/test_205_isomorphic_strings.py

@@ -0,0 +1,12 @@
+import pytest
+
+from awesome_python_leetcode._205_isomorphic_strings import Solution
+
+
+@pytest.mark.parametrize(
+    argnames=["s", "t", "expected"],
+    argvalues=[("egg", "add", True), ("foo", "bar", False), ("paper", "title", True)],
+)
+def test_func(s: str, t: str, expected: bool):
+    is_isomorphic = Solution().isIsomorphic(s, t)
+    assert is_isomorphic == expected