D. J.:

- Added the leetcode problem and solution for 20 Valid Parentheses

Author: nobodyPerfecZ

README.md

@@ -25,6 +25,7 @@ This repository contains awesome LeetCode problems and solutions written in Pyth
 ## Leetcode Problems & Solutions 💻
 
 - [1 Two Sum](https://leetcode.com/problems/two-sum/description/)
+- [20 Valid Parentheses](https://leetcode.com/problems/valid-parentheses/description/)
 - [26 Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/description/)
 - [27 Remove Element](https://leetcode.com/problems/remove-element/description/)
 - [45 Jump Game II](https://leetcode.com/problems/jump-game-ii/description/)

awesome_python_leetcode/_20_valid_parentheses.py

@@ -0,0 +1,24 @@
+class Solution:
+    def isValid(self, s: str) -> bool:
+        """
+        Given a string s containing just the characters '(', ')', '{', '}', '[' and ']',
+        determine if the input string is valid.
+
+        An input string is valid if:
+        1. Open brackets must be closed by the same type of brackets.
+        2. Open brackets must be closed in the correct order.
+        3. Every close bracket has a corresponding open bracket of the same type.
+        """
+        brackets = {"(": ")", "{": "}", "[": "]"}
+        stack = []
+        for bracket in s:
+            if bracket in brackets:
+                stack.append(bracket)
+            elif not stack:
+                return False
+            else:
+                open_bracket = stack.pop()
+                closed_bracket = brackets[open_bracket]
+                if closed_bracket != bracket:
+                    return False
+        return not stack

tests/test_20_valid_parentheses.py

@@ -0,0 +1,17 @@
+import pytest
+
+from awesome_python_leetcode._20_valid_parentheses import Solution
+
+
+@pytest.mark.parametrize(
+    argnames=["s", "expected"],
+    argvalues=[
+        ("()", True),
+        ("()[]{}", True),
+        ("(]", False),
+        ("([])", True),
+    ],
+)
+def test_func(s: str, expected: bool):
+    is_valid = Solution().isValid(s)
+    assert is_valid == expected