Add solution for "Valid Parentheses" and update README; add GitHub Actions workflow for README updates

Author: hantdev

.github/workflows/update_readme.yml

@@ -0,0 +1,34 @@
+name: Update README
+
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  update-readme:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.10'
+
+      - name: Install dependencies
+        run: pip install requests
+
+      - name: Run update script
+        run: python automata.py
+
+      - name: Commit and push changes
+        run: |
+          git config --global user.name "GitHub Action Bot"
+          git config --global user.email "github-actions[bot]@users.noreply.github.com"
+          git add README.md
+          git diff --staged --quiet || git commit -m "Auto-update README.md"
+          git push

.gitignore

@@ -0,0 +1 @@
+venv

README.md

@@ -4,9 +4,10 @@
 
 | # | Title | Solution | Type | Difficulty |
 |---| ----- | -------- | ---------- | ---------- |
-|0217|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/description/) | [Python](./array_hashing/0217-contains-duplicate.py)|Array & Hashing| Easy |
-|0242|[Valid Anagram](https://leetcode.com/problems/valid-anagram/description/) | [Python](./array_hashing/0242-valid-anagram.py)|Array & Hashing| Easy |
-|0001|[Two Sum](https://leetcode.com/problems/two-sum/description/) | [Python](./array_hashing/0001-two-sum.py)|Array & Hashing| Easy |
-|0049|[Group Anagrams](https://leetcode.com/problems/group-anagrams/description/) | [Python](./array_hashing/0049-group-anagrams.py)|Array & Hashing| Medium |
-|0125|[Valid Palindrome](https://leetcode.com/problems/valid-palindrome/description/) | [Python](./two_pointers/0125-valid-palindrome.py)|Two Pointers| Easy |
-|0347|[Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/description/) | [Python](./array_hashing/0347-top-k-frequent-elements.py)|Array & Hashing| Medium |
+|0001|[Two Sum](https://leetcode.com/problems/two-sum/description/)|[Python](./array_hashing/0001-two-sum.py)|Array Hashing| Easy |
+|0020|[Valid Parentheses](https://leetcode.com/problems/valid-parentheses/description/)|[Python](./stack/0020-valid-parentheses.py)|Stack| Easy |
+|0049|[Group Anagrams](https://leetcode.com/problems/group-anagrams/description/)|[Python](./array_hashing/0049-group-anagrams.py)|Array Hashing| Medium |
+|0125|[Valid Palindrome](https://leetcode.com/problems/valid-palindrome/description/)|[Python](./two_pointers/0125-valid-palindrome.py)|Two Pointers| Easy |
+|0217|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/description/)|[Python](./array_hashing/0217-contains-duplicate.py)|Array Hashing| Easy |
+|0242|[Valid Anagram](https://leetcode.com/problems/valid-anagram/description/)|[Python](./array_hashing/0242-valid-anagram.py)|Array Hashing| Easy |
+|0347|[Top K Frequent Elements](https://leetcode.com/problems/top-k-frequent-elements/description/)|[Python](./array_hashing/0347-top-k-frequent-elements.py)|Array Hashing| Medium |

automata.py

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+import os
+import re
+import requests
+
+def extract_problem_info(file_path):
+    match = re.match(r"(\d+)-([a-z0-9-]+)\.py", os.path.basename(file_path))
+    if match:
+        problem_number, slug = match.groups()
+        return int(problem_number), slug, f"[{slug.replace('-', ' ').title()}](https://leetcode.com/problems/{slug}/description/)"
+    return None, None, None
+
+def get_problem_difficulty(slug):
+    url = "https://leetcode.com/graphql"
+    query = """
+    query getQuestionDifficulty($titleSlug: String!) {
+      question(titleSlug: $titleSlug) {
+        difficulty
+      }
+    }
+    """
+    response = requests.post(url, json={"query": query, "variables": {"titleSlug": slug}})
+    try:
+        data = response.json()
+        return data["data"]["question"]["difficulty"]
+    except (KeyError, TypeError):
+        return "Unknown"
+
+def build_readme():
+    topics = [d for d in os.listdir('.') if os.path.isdir(d)]
+    problem_entries = []
+    
+    for topic in topics:
+        for file in os.listdir(topic):
+            if file.endswith(".py"):
+                problem_number, slug, problem_title = extract_problem_info(file)
+                if problem_number:
+                    difficulty = get_problem_difficulty(slug)
+                    problem_entries.append((problem_number, problem_title, f"[Python](./{topic}/{file})", topic.replace('_', ' ').title(), difficulty))
+    
+    problem_entries.sort()
+    
+    table_header = "| # | Title | Solution | Type | Difficulty |\n|---| ----- | -------- | ---------- | ---------- |"
+    table_rows = []
+    
+    for number, title, solution, topic, difficulty in problem_entries:
+        table_rows.append(f"|{number:04d}|{title}|{solution}|{topic}| {difficulty} |")
+    
+    table_content = "\n".join([table_header] + table_rows)
+    readme_content = f"""# Coding Everyday Until I Get A Job
+
+## LeetCode Solutions
+
+{table_content}
+"""
+    
+    with open("README.md", "w", encoding="utf-8") as f:
+        f.write(readme_content)
+
+if __name__ == "__main__":
+    build_readme()
+    print("README.md has been updated!")

requirements.txt

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+certifi==2025.1.31
+charset-normalizer==3.4.1
+idna==3.10
+requests==2.32.3
+urllib3==2.3.0