Merge pull request #8 from codewithme-py/feat/longest-palindromic-substring-0005

problem solution & test 0005

Author: codewithme-py

solutions/longest_palindromic_substring_0005.py

@@ -0,0 +1,30 @@
+class Solution:
+    def longestPalindrome(self, s: str) -> str:
+        """
+        Find the longest palindromic substring in the given string.
+        Args:
+            s: The input string.
+        Returns:
+            The longest palindromic substring in the input string.
+        """
+        start = 0
+        max_len = 1
+        if len(s) <= 1:
+            return s
+
+        def expand_around_center(left: int, right: int) -> tuple[int, int]:
+            while left >= 0 and right < len(s) and s[left] == s[right]:
+                left -= 1
+                right += 1
+            return right - left - 1, left + 1
+
+        for i in range(len(s)):
+            length_odd, start_odd = expand_around_center(i, i)
+            if length_odd > max_len:
+                max_len = length_odd
+                start = start_odd
+            length_even, start_even = expand_around_center(i, i + 1)
+            if length_even > max_len:
+                max_len = length_even
+                start = start_even
+        return s[start:start + max_len]

tests/test_longest_palindromic_substring_0005.py

@@ -0,0 +1,14 @@
+import pytest
+
+from solutions.longest_palindromic_substring_0005 import Solution
+
+
+@pytest.mark.parametrize('args, expected', [
+    ('babad', 'bab'),
+    ('cbbd', 'bb'),
+    ('a', 'a'),
+    ('ac', 'a')
+])
+def test_solution(args: str, expected: str) -> None:
+    sol = Solution()
+    assert sol.longestPalindrome(args) == expected