[ { "path": ".github/ISSUE_TEMPLATE/bug_report.yml", "content": "name: Bug Report\ndescription: Report a bug or issue with Leetcode Patterns\nlabels: [\"bug\"]\nbody:\n - type: textarea\n id: description\n attributes:\n label: Description\n description: A clear description of the bug.\n placeholder: Describe the issue...\n validations:\n required: true\n - type: textarea\n id: steps\n attributes:\n label: Steps to Reproduce\n description: How can we reproduce this issue?\n placeholder: |\n 1. Go to '...'\n 2. Click on '...'\n 3. See error\n validations:\n required: true\n - type: textarea\n id: expected\n attributes:\n label: Expected Behavior\n description: What did you expect to happen?\n validations:\n required: true\n - type: textarea\n id: screenshots\n attributes:\n label: Screenshots\n description: If applicable, add screenshots to help explain the issue.\n validations:\n required: false\n - type: dropdown\n id: browser\n attributes:\n label: Browser\n options:\n - Chrome\n - Firefox\n - Safari\n - Edge\n - Other\n validations:\n required: false\n" }, { "path": ".github/ISSUE_TEMPLATE/feature_request.yml", "content": "name: Feature Request\ndescription: Suggest a new feature or improvement\nlabels: [\"enhancement\"]\nbody:\n - type: textarea\n id: description\n attributes:\n label: Description\n description: A clear description of the feature you'd like.\n placeholder: I'd like to see...\n validations:\n required: true\n - type: textarea\n id: motivation\n attributes:\n label: Motivation\n description: Why would this feature be useful?\n validations:\n required: false\n - type: textarea\n id: alternatives\n attributes:\n label: Alternatives Considered\n description: Any alternative solutions or features you've considered.\n validations:\n required: false\n" }, { "path": ".github/ISSUE_TEMPLATE/question_request.yml", "content": "name: Question Request\ndescription: Request a new question to be added to the list\nlabels: [\"question-request\"]\nbody:\n - type: input\n id: title\n attributes:\n label: Question Title\n description: The title of the LeetCode question.\n placeholder: e.g. Two Sum\n validations:\n required: true\n - type: input\n id: url\n attributes:\n label: LeetCode URL\n description: Link to the question on LeetCode.\n placeholder: https://leetcode.com/problems/two-sum/\n validations:\n required: true\n - type: dropdown\n id: difficulty\n attributes:\n label: Difficulty\n options:\n - Easy\n - Medium\n - Hard\n validations:\n required: true\n - type: input\n id: pattern\n attributes:\n label: Pattern(s)\n description: Which pattern(s) does this question belong to?\n placeholder: e.g. Arrays, Two Pointers\n validations:\n required: true\n - type: textarea\n id: reason\n attributes:\n label: Why should this be added?\n description: Why is this question a good fit for the list?\n validations:\n required: false\n" }, { "path": ".github/workflows/ci.yml", "content": "name: CI\n\non:\n pull_request:\n types: [opened, synchronize, reopened, closed, labeled]\n branches: [main]\n\npermissions:\n contents: write\n pull-requests: write\n\njobs:\n lint:\n if: github.event.action != 'closed'\n runs-on: ubuntu-latest\n steps:\n - uses: actions/checkout@v4\n\n - uses: actions/setup-node@v4\n with:\n node-version: 22\n cache: npm\n\n - run: npm ci\n\n - run: npm run lint\n\n test:\n if: github.event.action != 'closed'\n runs-on: ubuntu-latest\n steps:\n - uses: actions/checkout@v4\n\n - uses: actions/setup-node@v4\n with:\n node-version: 22\n cache: npm\n\n - run: npm ci\n\n - run: npx vitest run --coverage\n\n preview:\n if: >-\n always() &&\n contains(github.event.pull_request.labels.*.name, 'preview') &&\n (github.event.action == 'closed' || (needs.lint.result == 'success' && needs.test.result == 'success'))\n needs: [lint, test]\n runs-on: ubuntu-latest\n steps:\n - uses: actions/checkout@v4\n\n - if: github.event.action != 'closed'\n uses: actions/setup-node@v4\n with:\n node-version: 22\n cache: npm\n\n - if: github.event.action != 'closed'\n run: npm ci\n\n - if: github.event.action != 'closed'\n name: Build\n env:\n NEXT_PUBLIC_BASE_PATH: /leetcode-patterns/pr-preview/pr-${{ github.event.number }}\n NEXT_PUBLIC_SUPABASE_URL: ${{ secrets.NEXT_PUBLIC_SUPABASE_URL }}\n NEXT_PUBLIC_SUPABASE_ANON_KEY: ${{ secrets.NEXT_PUBLIC_SUPABASE_ANON_KEY }}\n run: npx next build\n\n - if: github.event.action != 'closed'\n name: Remove service worker from preview\n run: rm -f out/sw.js\n\n - uses: rossjrw/pr-preview-action@v1\n with:\n source-dir: out\n" }, { "path": ".github/workflows/deploy.yml", "content": "name: Deploy to GitHub Pages\n\non:\n push:\n branches: [main]\n\n workflow_run:\n workflows: [Update Questions]\n types:\n - completed\n\n workflow_dispatch:\n\npermissions:\n contents: write\n\njobs:\n deploy:\n runs-on: ubuntu-latest\n steps:\n - uses: actions/checkout@v4\n\n - uses: actions/setup-node@v4\n with:\n node-version: 22\n cache: npm\n\n - run: npm ci\n\n - name: Build\n env:\n NEXT_PUBLIC_BASE_PATH: /leetcode-patterns\n NEXT_PUBLIC_SUPABASE_URL: ${{ secrets.NEXT_PUBLIC_SUPABASE_URL }}\n NEXT_PUBLIC_SUPABASE_ANON_KEY: ${{ secrets.NEXT_PUBLIC_SUPABASE_ANON_KEY }}\n run: npm run build\n\n - uses: JamesIves/github-pages-deploy-action@v4\n with:\n folder: out\n branch: gh-pages\n clean-exclude: pr-preview\n force: false\n" }, { "path": ".github/workflows/update-questions.yml", "content": "name: Update Questions\n\non:\n schedule:\n # Every Sunday at 8am EST (1pm UTC)\n - cron: \"0 13 * * 0\"\n workflow_dispatch:\n\npermissions:\n contents: write\n\njobs:\n update:\n runs-on: ubuntu-latest\n steps:\n - uses: actions/checkout@v4\n\n - uses: actions/setup-python@v5\n with:\n python-version: \"3.12\"\n\n - name: Update question metadata\n working-directory: cron\n env:\n LEETCODE_SESSION_TOKEN: ${{ secrets.LEETCODE_SESSION_TOKEN }}\n LEETCODE_CSRF_TOKEN: ${{ secrets.LEETCODE_CSRF_TOKEN }}\n LEETCODE_CF_CLEARANCE: ${{ secrets.LEETCODE_CF_CLEARANCE }}\n run: python update_questions.py\n\n - name: Commit and push changes\n run: |\n git config user.name \"github-actions[bot]\"\n git config user.email \"github-actions[bot]@users.noreply.github.com\"\n git add src/data/questions.json\n git diff --cached --quiet || git commit --author=\"Sean Prashad <13009507+seanprashad@users.noreply.github.com>\" -m \"chore: update question metadata\" && git push\n" }, { "path": ".gitignore", "content": "# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.\n\n# dependencies\n/node_modules\n/.pnp\n.pnp.*\n.yarn/*\n!.yarn/patches\n!.yarn/plugins\n!.yarn/releases\n!.yarn/versions\n\n# testing\n/coverage\n\n# next.js\n/.next/\n/out/\n\n# production\n/build\n\n# misc\n.DS_Store\n*.pem\n\n# debug\nnpm-debug.log*\nyarn-debug.log*\nyarn-error.log*\n.pnpm-debug.log*\n\n# env files (can opt-in for committing if needed)\n.env*\n\n# vercel\n.vercel\n\n# typescript\n*.tsbuildinfo\nnext-env.d.ts\n\n# python\n__pycache__\n" }, { "path": ".husky/pre-push", "content": "npm run lint -- --fix\nnpm test\n" }, { "path": ".npmrc", "content": "registry=https://registry.npmjs.org\n" }, { "path": "LICENSE", "content": "Creative Commons Attribution-NonCommercial 4.0 International\n\nCopyright (c) 2026 Sean Prashad\n\nThis work is licensed under the Creative Commons\nAttribution-NonCommercial 4.0 International License.\n\nYou are free to:\n\n Share — copy and redistribute the material in any medium or format\n Adapt — remix, transform, and build upon the material\n\nUnder the following terms:\n\n Attribution — You must give appropriate credit, provide a link to\n the license, and indicate if changes were made. You may do so in\n any reasonable manner, but not in any way that suggests the licensor\n endorses you or your use.\n\n NonCommercial — You may not use the material for commercial purposes.\n\n No additional restrictions — You may not apply legal terms or\n technological measures that legally restrict others from doing\n anything the license permits.\n\nNotices:\n\n You do not have to comply with the license for elements of the\n material in the public domain or where your use is permitted by an\n applicable exception or limitation.\n\n No warranties are given. The license may not give you all of the\n permissions necessary for your intended use. For example, other\n rights such as publicity, privacy, or moral rights may limit how\n you use the material.\n\nFull license text:\nhttps://creativecommons.org/licenses/by-nc/4.0/legalcode\n" }, { "path": "README.md", "content": "

\n \n \n \n \"Leetcode\n \n

\n\n

\n \"Deploy\n \"Update\n

\n\n## Table of Contents\n\n- [Background](#background)\n- [Fundamentals](#fundamentals)\n- [Notes](#notes)\n- [Question List](#question-list)\n- [Solutions](#solutions)\n- [Contributing](#contributing)\n- [Suggestions](#suggestions)\n- [Acknowledgements](#acknowledgements)\n\n## Background\n\nThis repo is intended for any individual wanting to improve their problem\nsolving skills for software engineering interviews.\n\nProblems are grouped under their respective subtopic, in order to focus on\nrepeatedly applying common patterns rather than randomly tackling questions.\n\nAll questions are available on [leetcode.com] with some requiring [leetcode premium].\n\n## Fundamentals\n\nTo find the greatest amount of success when practicing, it is highly recommended\nto know the methods and runtimes of the following data structures and their\noperations:\n\n- Arrays\n- Maps\n- Linked Lists\n- Queues\n- Heaps\n- Stacks\n- Trees\n- Graphs\n\nIn addition, you should have a good grasp on common algorithms such as:\n\n- Breadth-first search\n- Depth-first search\n- Binary search\n- Recursion\n\n## Notes\n\n[This pdf] contains information for the main data structures in Java.\n\nOther useful methods to know include [`substring()`](https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#substring-int-int-), [`toCharArray()`](https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#toCharArray--), [`Math.max()`](https://docs.oracle.com/javase/8/docs/api/java/lang/Math.html#max-int-int-),\n[`Math.min()`](https://docs.oracle.com/javase/8/docs/api/java/lang/Math.html#min-int-int-), and [`Arrays.fill()`](https://docs.oracle.com/javase/8/docs/api/java/util/Arrays.html#fill-int:A-int-).\n\n## Question List\n\nThe entire question list can be found here:\nhttps://seanprashad.com/leetcode-patterns/.\n\n## Solutions\n\nSolutions written in Java can be found in the [solutions] branch.\n\n## Contributing\n\nThe app is built with [Next.js] (App Router), [React] 19, [TypeScript], [Tailwind CSS] v4, [TanStack Table] v8, [Lucide React] for icons, and Google Analytics via `@next/third-parties`. Tests use [Vitest] + [React Testing Library].\n\n```bash\nnpm install\nnpm run dev # http://localhost:3000\nnpm test # single run\nnpm run test:watch # watch mode\n```\n\nA [Husky] `pre-push` hook runs `npm test` automatically before every push. This is set up for every clone via the `prepare` script.\n\n## Acknowledgements\n\nThis list is heavily inspired from [Grokking the Coding Interview] with\nadditional problems extracted from the [Blind 75 list] and this hackernoon article\non [14 patterns to ace any coding interview question].\n\n[leetcode.com]: https://leetcode.com\n[leetcode premium]: https://leetcode.com/subscribe/\n[next.js]: https://nextjs.org\n[react]: https://react.dev\n[typescript]: https://www.typescriptlang.org\n[tailwind css]: https://tailwindcss.com\n[tanstack table]: https://tanstack.com/table\n[lucide react]: https://lucide.dev\n[vitest]: https://vitest.dev\n[react testing library]: https://testing-library.com/docs/react-testing-library/intro\n[husky]: https://typicode.github.io/husky\n[this pdf]: https://drive.google.com/open?id=1ao4ZA28zzBttDkuS6MLQI52gDs_CJZEm\n[solutions]: https://github.com/SeanPrashad/leetcode-patterns/tree/solutions\n[grokking the coding interview]: https://www.educative.io/courses/grokking-the-coding-interview\n[issue]: https://github.com/SeanPrashad/leetcode-patterns/issues/new\n[blind 75 list]: https://www.teamblind.com/article/New-Year-Gift---Curated-List-of-Top-100-LeetCode-Questions-to-Save-Your-Time-OaM1orEU?utm_source=share&utm_medium=ios_app\n[14 patterns to ace any coding interview question]: https://hackernoon.com/14-patterns-to-ace-any-coding-interview-question-c5bb3357f6ed\n" }, { "path": "cron/leetcode/__init__.py", "content": "from leetcode.models import (\n Configuration,\n ApiClient,\n DefaultApi,\n GraphqlQuery,\n GraphqlQueryGetQuestionDetailVariables,\n GraphqlQuestionDetail,\n GraphqlData,\n GraphqlResponse,\n)\n\nfrom leetcode import auth\nfrom leetcode import rest\n\n__all__ = [\n \"Configuration\",\n \"ApiClient\",\n \"DefaultApi\",\n \"GraphqlQuery\",\n \"GraphqlQueryGetQuestionDetailVariables\",\n \"GraphqlQuestionDetail\",\n \"GraphqlData\",\n \"GraphqlResponse\",\n \"auth\",\n \"rest\",\n]\n" }, { "path": "cron/leetcode/auth.py", "content": "# Placeholder for leetcode.auth compatibility.\n# Authentication is handled via Configuration.api_key in the main module.\n" }, { "path": "cron/leetcode/models.py", "content": "import json\nimport urllib.request\n\nfrom leetcode.rest import ApiException\n\n\nclass Configuration:\n def __init__(self):\n self.host = \"https://leetcode.com\"\n self.api_key = {}\n self.debug = False\n\n\nclass GraphqlQuery:\n def __init__(self, query=None, variables=None, operation_name=None):\n self.query = query\n self.variables = variables\n self.operation_name = operation_name\n\n\nclass GraphqlQueryGetQuestionDetailVariables:\n def __init__(self, title_slug=None):\n self.title_slug = title_slug\n\n\nclass GraphqlQuestionDetail:\n def __init__(self, question_id=None, title=None, difficulty=None,\n company_tag_stats_v2=None, is_paid_only=None, topic_tags=None):\n self.question_id = question_id\n self.title = title\n self.difficulty = difficulty\n self.company_tag_stats_v2 = company_tag_stats_v2\n self.is_paid_only = is_paid_only\n self.topic_tags = topic_tags\n\n\nclass GraphqlData:\n def __init__(self, question=None):\n self.question = question\n\n\nclass GraphqlResponse:\n def __init__(self, data=None):\n self.data = data\n\n\nclass ApiClient:\n def __init__(self, configuration=None):\n self.configuration = configuration or Configuration()\n\n\nclass DefaultApi:\n def __init__(self, api_client=None):\n self.api_client = api_client or ApiClient()\n\n def graphql_post(self, body=None):\n config = self.api_client.configuration\n\n variables = {}\n if body.variables and hasattr(body.variables, \"title_slug\"):\n variables[\"titleSlug\"] = body.variables.title_slug\n\n payload = {\"query\": body.query, \"variables\": variables}\n if body.operation_name:\n payload[\"operationName\"] = body.operation_name\n\n data = json.dumps(payload).encode(\"utf-8\")\n\n cookie = (\n f\"csrftoken={config.api_key.get('csrftoken') or ''}; \"\n f\"LEETCODE_SESSION={config.api_key.get('LEETCODE_SESSION') or ''}; \"\n f\"cf_clearance={config.api_key.get('cf_clearance') or ''}\"\n )\n\n url = config.host + \"/graphql\"\n req = urllib.request.Request(url, data=data, method=\"POST\")\n req.add_header(\"Content-Type\", \"application/json\")\n req.add_header(\"Accept\", \"application/json\")\n req.add_header(\"User-Agent\", \"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36\")\n req.add_header(\"x-csrftoken\", config.api_key.get(\"x-csrftoken\") or \"\")\n req.add_header(\"Referer\", config.api_key.get(\"Referer\") or \"https://leetcode.com\")\n req.add_header(\"Cookie\", cookie)\n\n try:\n with urllib.request.urlopen(req) as resp:\n resp_data = json.loads(resp.read().decode(\"utf-8\"))\n except urllib.error.HTTPError as e:\n raise ApiException(\n status=e.code,\n reason=e.reason,\n body=e.read().decode(\"utf-8\"),\n )\n\n question_data = resp_data.get(\"data\", {}).get(\"question\", {})\n\n topic_tags_raw = question_data.get(\"topicTags\")\n topic_tags = [type(\"Tag\", (), {\"name\": t[\"name\"]}) for t in topic_tags_raw]\n\n question = GraphqlQuestionDetail(\n question_id=question_data.get(\"questionId\"),\n title=question_data.get(\"title\"),\n difficulty=question_data.get(\"difficulty\"),\n company_tag_stats_v2=question_data.get(\"companyTagStatsV2\"),\n is_paid_only=question_data.get(\"isPaidOnly\"),\n topic_tags=topic_tags,\n )\n\n return GraphqlResponse(data=GraphqlData(question=question))\n" }, { "path": "cron/leetcode/rest.py", "content": "class ApiException(Exception):\n def __init__(self, status=None, reason=None, body=None):\n self.status = status\n self.reason = reason\n self.body = body\n\n def __str__(self):\n msg = f\"({self.status})\\nReason: {self.reason}\\n\"\n if self.body:\n msg += f\"HTTP response body: {self.body}\\n\"\n return msg\n" }, { "path": "cron/update_questions.py", "content": "import os\nimport json\nimport leetcode\nimport leetcode.auth\nfrom datetime import datetime\nfrom leetcode.rest import ApiException\n\n\ndef create_leetcode_api():\n leetcode_session_token = os.environ.get(\"LEETCODE_SESSION_TOKEN\")\n csrf_token = os.environ.get(\"LEETCODE_CSRF_TOKEN\")\n cf_clearance = os.environ.get(\"LEETCODE_CF_CLEARANCE\")\n\n if not leetcode_session_token:\n print(\"❌ LEETCODE_SESSION_TOKEN environment variable is required\")\n exit(1)\n\n if not csrf_token:\n print(\"❌ LEETCODE_CSRF_TOKEN environment variable is required\")\n exit(1)\n\n if not cf_clearance:\n print(\"❌ LEETCODE_CF_CLEARANCE environment variable is required\")\n exit(1)\n\n configuration = leetcode.Configuration()\n\n configuration.api_key[\"x-csrftoken\"] = csrf_token\n configuration.api_key[\"csrftoken\"] = csrf_token\n configuration.api_key[\"LEETCODE_SESSION\"] = leetcode_session_token\n configuration.api_key[\"cf_clearance\"] = cf_clearance\n configuration.api_key[\"Referer\"] = \"https://leetcode.com\"\n configuration.debug = False\n\n return leetcode.DefaultApi(leetcode.ApiClient(configuration))\n\n\ndef get_question_metadata(api, title_slug):\n graphql_request = leetcode.GraphqlQuery(\n query='''query questionData($titleSlug: String!) {\n question(titleSlug: $titleSlug) {\n questionId\n title\n difficulty\n companyTagStatsV2\n isPaidOnly\n topicTags {\n name\n }\n }\n }\n ''',\n variables=leetcode.GraphqlQueryGetQuestionDetailVariables(\n title_slug=title_slug)\n )\n\n try:\n response = api.graphql_post(body=graphql_request)\n if not response.data.question:\n print(f'❌ Empty response body for question: {title_slug}')\n exit(1)\n return response\n except ApiException as e:\n print(\n f'Exception occurred when contacting the Leetcode GraphQL API: ${e}')\n exit()\n\n\ndef construct_company_tag_list(company_tag_stats_v2):\n companies = []\n\n tag_stats = json.loads(company_tag_stats_v2)\n # \"three_months\" = 0-3 months, \"six_months\" = 3-6 months, \"more_than_six_months\" = 6+ months\n for tag in tag_stats[\"three_months\"] + tag_stats[\"six_months\"]:\n companies.append({\n \"name\": tag[\"name\"],\n \"slug\": tag[\"slug\"],\n \"frequency\": tag[\"timesEncountered\"]\n })\n\n return sorted(companies, key=lambda d: d['frequency'], reverse=True)\n\n\ndef update_question_metadata(question, response):\n print(f'''🔄 Updating question metadata for {question[\"title\"]}''')\n\n question_id = response.data.question.question_id\n question_title = response.data.question.title\n question_difficulty = response.data.question.difficulty\n question_company_tag_stats_v2 = response.data.question.company_tag_stats_v2\n question_is_premium = response.data.question.is_paid_only\n question_topic_tags = response.data.question.topic_tags\n\n companies = construct_company_tag_list(question_company_tag_stats_v2)\n patterns = [tag.name for tag in question_topic_tags]\n\n question[\"id\"] = int(question_id)\n question[\"title\"] = question_title\n question[\"difficulty\"] = question_difficulty\n question[\"pattern\"] = patterns\n question[\"companies\"] = companies\n question[\"premium\"] = question_is_premium\n\n\ndef read_questions(file_name):\n print(f\"💾 Loading {file_name}\")\n\n try:\n with open(file_name, \"r\") as file:\n questions = json.load(file)\n print(f\"✅ Finished loading {file_name}\")\n return questions\n except Exception as e:\n print(\n f\"❌ Exception occurred when reading {file_name}: {e}\")\n exit()\n\n\ndef write_questions(file_name, questions):\n print(f\"💾 Updating {file_name}\")\n\n try:\n with open(file_name, \"w\") as file:\n questions[\"updated\"] = str(datetime.now().isoformat())\n json.dump(questions, file, indent=2)\n print(f\"✅ Finished updating {file_name}\")\n except Exception as e:\n print(\n f\"❌ Exception occurred when writing {file_name}: {e}\")\n exit()\n\n\ndef main(file_name):\n api = create_leetcode_api()\n questions = read_questions(file_name)\n\n for question in questions[\"data\"]:\n title_slug = question[\"slug\"]\n\n response = get_question_metadata(api, title_slug)\n\n update_question_metadata(question, response)\n\n write_questions(file_name, questions)\n\n\nif __name__ == \"__main__\":\n file_name = os.path.join(os.path.dirname(os.path.abspath(__file__)), \"..\", \"src\", \"data\", \"questions.json\")\n startTime = datetime.now()\n\n main(file_name)\n\n print(f\"⏱️ Data updated in {datetime.now() - startTime} seconds\")\n" }, { "path": "eslint.config.mjs", "content": "import { defineConfig, globalIgnores } from \"eslint/config\";\nimport nextVitals from \"eslint-config-next/core-web-vitals\";\nimport nextTs from \"eslint-config-next/typescript\";\n\nconst eslintConfig = defineConfig([\n ...nextVitals,\n ...nextTs,\n // Override default ignores of eslint-config-next.\n globalIgnores([\n // Default ignores of eslint-config-next:\n \".next/**\",\n \"out/**\",\n \"build/**\",\n \"next-env.d.ts\",\n ]),\n]);\n\nexport default eslintConfig;\n" }, { "path": "next.config.ts", "content": "import type { NextConfig } from \"next\";\n\nconst nextConfig: NextConfig = {\n reactStrictMode: false,\n output: \"export\",\n trailingSlash: false,\n basePath: process.env.NEXT_PUBLIC_BASE_PATH ?? \"\",\n images: { unoptimized: true },\n};\n\nexport default nextConfig;\n" }, { "path": "package.json", "content": "{\n \"name\": \"leetcode-patterns-v2\",\n \"version\": \"0.1.0\",\n \"private\": true,\n \"scripts\": {\n \"dev\": \"next dev\",\n \"build\": \"next build && node scripts/generate-sw-precache.mjs\",\n \"start\": \"next start\",\n \"lint\": \"eslint\",\n \"test\": \"vitest run\",\n \"test:watch\": \"vitest\",\n \"prepare\": \"husky\"\n },\n \"dependencies\": {\n \"@next/third-parties\": \"^16.1.6\",\n \"@supabase/supabase-js\": \"^2.99.0\",\n \"@tanstack/react-table\": \"^8.21.3\",\n \"@tanstack/react-virtual\": \"^3.13.21\",\n \"lucide-react\": \"^0.577.0\",\n \"next\": \"16.1.7\",\n \"react\": \"19.2.3\",\n \"react-dom\": \"19.2.3\"\n },\n \"devDependencies\": {\n \"@tailwindcss/postcss\": \"^4\",\n \"@testing-library/jest-dom\": \"^6.9.1\",\n \"@testing-library/react\": \"^16.3.2\",\n \"@testing-library/user-event\": \"^14.6.1\",\n \"@types/node\": \"^20\",\n \"@types/react\": \"^19\",\n \"@types/react-dom\": \"^19\",\n \"@vitejs/plugin-react\": \"^5.1.4\",\n \"@vitest/coverage-v8\": \"^4.0.18\",\n \"eslint\": \"^9\",\n \"eslint-config-next\": \"16.1.6\",\n \"happy-dom\": \"^20.8.3\",\n \"husky\": \"^9.1.7\",\n \"jsdom\": \"^28.1.0\",\n \"tailwindcss\": \"^4\",\n \"typescript\": \"^5\",\n \"vitest\": \"^4.0.18\"\n }\n}\n" }, { "path": "postcss.config.mjs", "content": "const config = {\n plugins: {\n \"@tailwindcss/postcss\": {},\n },\n};\n\nexport default config;\n" }, { "path": "public/.nojekyll", "content": "\n" }, { "path": "public/manifest.json", "content": "{\n \"short_name\": \"leetcode-patterns\",\n \"name\": \"Leetcode Patterns\",\n \"description\": \"A curated list of LeetCode questions grouped by patterns.\",\n \"icons\": [\n {\n \"src\": \"favicon.ico\",\n \"sizes\": \"64x64 32x32 24x24 16x16\",\n \"type\": \"image/x-icon\"\n }\n ],\n \"start_url\": \".\",\n \"display\": \"standalone\",\n \"theme_color\": \"#09090b\",\n \"background_color\": \"#ffffff\"\n}\n" }, { "path": "public/robots.txt", "content": "User-agent: *\nAllow: /\n" }, { "path": "public/sw.js", "content": "// Service Worker — cache-first for static assets, network-first for navigation\nconst CACHE_NAME = \"lc-patterns-v2\";\n\nconst PRECACHE_URLS = [\n \"./\",\n \"./manifest.json\",\n];\n\nself.addEventListener(\"install\", (event) => {\n event.waitUntil(\n caches.open(CACHE_NAME).then((cache) => cache.addAll(PRECACHE_URLS))\n );\n self.skipWaiting();\n});\n\nself.addEventListener(\"activate\", (event) => {\n event.waitUntil(\n caches.keys().then((keys) =>\n Promise.all(keys.filter((k) => k !== CACHE_NAME).map((k) => caches.delete(k)))\n )\n );\n self.clients.claim();\n});\n\nself.addEventListener(\"fetch\", (event) => {\n const { request } = event;\n\n // Skip non-GET and chrome-extension requests\n if (request.method !== \"GET\" || !request.url.startsWith(\"http\")) return;\n\n // Skip analytics and external API calls\n if (\n request.url.includes(\"google-analytics.com\") ||\n request.url.includes(\"googletagmanager.com\") ||\n request.url.includes(\"s2/favicons\")\n ) return;\n\n // Navigation requests: network-first with cache fallback\n if (request.mode === \"navigate\") {\n event.respondWith(\n fetch(request)\n .then((response) => {\n const clone = response.clone();\n caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));\n return response;\n })\n .catch(() => caches.match(request).then((cached) => cached || caches.match(\"./\")))\n );\n return;\n }\n\n // Static assets: cache-first with network fallback\n event.respondWith(\n caches.match(request).then(\n (cached) =>\n cached ||\n fetch(request).then((response) => {\n // Only cache successful same-origin responses\n if (response.ok && request.url.startsWith(self.location.origin)) {\n const clone = response.clone();\n caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));\n }\n return response;\n })\n )\n );\n});\n" }, { "path": "scripts/generate-sw-precache.mjs", "content": "import { readFileSync, writeFileSync, readdirSync, statSync } from \"fs\";\nimport { join, relative } from \"path\";\n\nconst OUT_DIR = \"out\";\nconst SW_PATH = join(OUT_DIR, \"sw.js\");\n\nconst PRECACHE_EXTENSIONS = new Set([\n \".html\", \".js\", \".css\", \".json\", \".txt\", \".woff\", \".woff2\",\n]);\n\nfunction collectFiles(dir, base = dir) {\n const entries = [];\n for (const entry of readdirSync(dir)) {\n const full = join(dir, entry);\n if (statSync(full).isDirectory()) {\n entries.push(...collectFiles(full, base));\n } else {\n const rel = \"./\" + relative(base, full);\n if (rel === \"./sw.js\") continue;\n if (rel.endsWith(\".map\")) continue;\n const ext = rel.slice(rel.lastIndexOf(\".\"));\n if (!PRECACHE_EXTENSIONS.has(ext)) continue;\n entries.push(rel);\n }\n }\n return entries;\n}\n\nconst files = collectFiles(OUT_DIR);\nconst sw = readFileSync(SW_PATH, \"utf-8\");\n\n// Replace the placeholder PRECACHE_URLS array with the full file list\nconst updated = sw.replace(\n /const PRECACHE_URLS = \\[[\\s\\S]*?\\];/,\n `const PRECACHE_URLS = ${JSON.stringify(files, null, 2)};`\n);\n\nwriteFileSync(SW_PATH, updated);\nconsole.log(`Precache manifest: ${files.length} files injected into sw.js`);\n" }, { "path": "src/app/globals.css", "content": "@import \"tailwindcss\";\n\n@custom-variant dark (&:where(.dark, .dark *));\n\n:root {\n --background: #ffffff;\n --foreground: #171717;\n}\n\n.dark {\n --background: #0a0a0a;\n --foreground: #ededed;\n}\n\n@theme inline {\n --color-background: var(--background);\n --color-foreground: var(--foreground);\n --font-sans: var(--font-geist-sans);\n --font-mono: var(--font-geist-mono);\n}\n\nbody {\n background: var(--background);\n color: var(--foreground);\n font-family: Arial, Helvetica, sans-serif;\n}\n\n@keyframes fadeInUp {\n from {\n opacity: 0;\n transform: translateY(1rem);\n }\n to {\n opacity: 1;\n transform: translateY(0);\n }\n}\n" }, { "path": "src/app/layout.tsx", "content": "import type { Metadata } from \"next\";\nimport { GoogleAnalytics } from \"@next/third-parties/google\";\nimport { Geist, Geist_Mono, Dancing_Script } from \"next/font/google\";\nimport \"./globals.css\";\nimport ServiceWorkerRegistrar from \"@/components/layout/ServiceWorkerRegistrar\";\nimport { AuthProvider } from \"@/components/layout/AuthContext\";\n\nconst geistSans = Geist({\n variable: \"--font-geist-sans\",\n subsets: [\"latin\"],\n});\n\nconst geistMono = Geist_Mono({\n variable: \"--font-geist-mono\",\n subsets: [\"latin\"],\n});\n\nconst dancingScript = Dancing_Script({\n variable: \"--font-dancing-script\",\n subsets: [\"latin\"],\n});\n\nconst siteUrl = \"https://seanprashad.com/leetcode-patterns\";\nconst basePath = process.env.NEXT_PUBLIC_BASE_PATH ?? \"\";\n\nexport const metadata: Metadata = {\n title: \"Leetcode Patterns\",\n description:\n \"A curated list of LeetCode questions grouped by pattern to help you ace coding interviews. Filter by difficulty, company, and topic.\",\n manifest: `${basePath}/manifest.json`,\n metadataBase: new URL(siteUrl),\n alternates: { canonical: \"/\" },\n openGraph: {\n title: \"Leetcode Patterns\",\n description:\n \"A curated list of LeetCode questions grouped by pattern to help you ace coding interviews.\",\n url: siteUrl,\n siteName: \"Leetcode Patterns\",\n images: [\n {\n url: `${basePath}/images/og-image.png`,\n width: 1200,\n height: 630,\n alt: \"Leetcode Patterns – A curated list of LeetCode questions grouped by pattern\",\n },\n ],\n type: \"website\",\n },\n twitter: {\n card: \"summary_large_image\",\n title: \"Leetcode Patterns\",\n description:\n \"A curated list of LeetCode questions grouped by pattern to help you ace coding interviews.\",\n images: [`${basePath}/images/og-image.png`],\n },\n keywords: [\n \"leetcode\",\n \"coding interview\",\n \"data structures\",\n \"algorithms\",\n \"interview prep\",\n \"blind 75\",\n \"leetcode patterns\",\n ],\n authors: [{ name: \"Sean Prashad\", url: \"https://github.com/SeanPrashad\" }],\n};\n\nexport default function RootLayout({\n children,\n}: Readonly<{\n children: React.ReactNode;\n}>) {\n return (\n \n \n -1)window.__SUPABASE_AUTH_HASH__=location.hash`,\n }}\n />\n \n \n \n {children}\n \n \n \n \n \n );\n}\n" }, { "path": "src/app/not-found.tsx", "content": "import Link from \"next/link\";\n\nexport default function NotFound() {\n return (\n
\n
\n \n 404\n
\n

Page not found

\n

\n The page you're looking for doesn't exist.\n

\n \n ← Back to questions\n \n
\n \n );\n}\n" }, { "path": "src/app/page.tsx", "content": "import { Suspense } from \"react\";\nimport { MessageSquarePlus } from \"lucide-react\";\nimport ThemeToggle from \"@/components/layout/ThemeToggle\";\nimport GitHubLink from \"@/components/layout/GitHubLink\";\nimport UserMenu from \"@/components/layout/UserMenu\";\nimport Logo from \"@/components/layout/Logo\";\nimport ViewSwitcher from \"@/components/layout/ViewSwitcher\";\nimport AboutPanel from \"@/components/panels/AboutPanel\";\nimport AcknowledgementsPanel from \"@/components/panels/AcknowledgementsPanel\";\nimport TipsPanel from \"@/components/panels/TipsPanel\";\nimport questionsJson from \"@/data/questions.json\";\nimport { QuestionsData } from \"@/types/question\";\n\nconst { data: questions } = questionsJson as QuestionsData;\n\nexport default function Home() {\n return (\n
\n
\n
\n

\n \n

\n

\n by{\" \"}\n \n Sean Prashad\n \n {\" · Est. 2019\"}\n

\n

\n A collection of {questions.length} questions grouped by pattern to help you prepare for coding interviews.\n

\n
\n
\n \n \n \n \n \n \n Feedback\n \n \n \n \n
\n
\n {/* Side panel tabs – stacked flush in a fixed column */}\n
\n \n \n \n
\n \n \n \n
\n );\n}\n" }, { "path": "src/components/layout/AuthContext.test.tsx", "content": "import { describe, it, expect, vi, beforeEach, afterEach } from \"vitest\";\nimport { render, screen, cleanup, act } from \"@testing-library/react\";\n\ntype AuthCallback = (event: string, session: { user: Record } | null) => void;\n\nconst { mockGetSession, mockOnAuthStateChange, mockTrackEvent, mockDownloadAndMerge, mockChannel } = vi.hoisted(() => {\n const mockChannel = {\n on: vi.fn().mockReturnThis(),\n subscribe: vi.fn().mockReturnThis(),\n };\n return {\n mockGetSession: vi.fn(),\n mockOnAuthStateChange: vi.fn(),\n mockTrackEvent: vi.fn(),\n mockDownloadAndMerge: vi.fn(() => Promise.resolve()),\n mockChannel,\n };\n});\n\nvi.mock(\"@/lib/supabase\", () => ({\n supabase: {\n auth: {\n getSession: mockGetSession,\n onAuthStateChange: mockOnAuthStateChange,\n setSession: vi.fn(),\n },\n channel: () => mockChannel,\n removeChannel: vi.fn(),\n },\n}));\n\nvi.mock(\"@/lib/sync\", () => ({\n downloadAndMerge: mockDownloadAndMerge,\n scheduleUpload: vi.fn(),\n mergeFromRealtimePayload: vi.fn(),\n}));\n\nvi.mock(\"@/lib/analytics\", () => ({\n trackEvent: mockTrackEvent,\n}));\n\nimport { AuthProvider, useAuth } from \"@/components/layout/AuthContext\";\n\nconst fakeUser = {\n id: \"user-1\",\n user_metadata: { user_name: \"testuser\", avatar_url: \"https://example.com/avatar.png\" },\n};\n\nfunction TestConsumer() {\n const { user } = useAuth();\n return
{user ? `signed-in:${(user as unknown as typeof fakeUser).user_metadata.user_name}` : \"signed-out\"}
;\n}\n\ndescribe(\"AuthProvider sign-in toast suppression\", () => {\n let authCallback: AuthCallback;\n const unsubscribe = vi.fn();\n\n beforeEach(() => {\n mockTrackEvent.mockClear();\n mockDownloadAndMerge.mockClear();\n mockOnAuthStateChange.mockImplementation((cb: AuthCallback) => {\n authCallback = cb;\n return { data: { subscription: { unsubscribe } } };\n });\n });\n\n afterEach(() => {\n cleanup();\n vi.restoreAllMocks();\n });\n\n it(\"shows toast on fresh sign-in when no existing session\", async () => {\n mockGetSession.mockResolvedValue({ data: { session: null } });\n\n await act(async () => {\n render(\n \n \n \n );\n });\n\n expect(screen.getByText(\"signed-out\")).toBeInTheDocument();\n\n await act(async () => {\n authCallback(\"SIGNED_IN\", { user: fakeUser });\n });\n\n expect(screen.getByText(/Signed in as testuser/)).toBeInTheDocument();\n expect(mockTrackEvent).toHaveBeenCalledWith(\"sign_in\", { provider: \"github\" });\n });\n\n it(\"does NOT show toast when session already exists and SIGNED_IN fires again\", async () => {\n mockGetSession.mockResolvedValue({ data: { session: { user: fakeUser } } });\n\n await act(async () => {\n render(\n \n \n \n );\n });\n\n expect(screen.getByText(\"signed-in:testuser\")).toBeInTheDocument();\n mockTrackEvent.mockClear();\n\n await act(async () => {\n authCallback(\"SIGNED_IN\", { user: fakeUser });\n });\n\n expect(screen.queryByText(/Signed in as/)).not.toBeInTheDocument();\n expect(mockTrackEvent).not.toHaveBeenCalledWith(\"sign_in\", expect.anything());\n });\n\n it(\"does NOT show toast when INITIAL_SESSION fires before getSession resolves\", async () => {\n // Simulate getSession that never resolves before INITIAL_SESSION fires\n let resolveGetSession!: (v: { data: { session: { user: typeof fakeUser } } }) => void;\n mockGetSession.mockReturnValue(new Promise((r) => { resolveGetSession = r; }));\n\n await act(async () => {\n render(\n \n \n \n );\n });\n\n // Supabase fires INITIAL_SESSION before getSession resolves\n await act(async () => {\n authCallback(\"INITIAL_SESSION\", { user: fakeUser });\n });\n\n // Then SIGNED_IN fires (common Supabase behaviour on page load)\n await act(async () => {\n authCallback(\"SIGNED_IN\", { user: fakeUser });\n });\n\n expect(screen.queryByText(/Signed in as/)).not.toBeInTheDocument();\n expect(mockTrackEvent).not.toHaveBeenCalledWith(\"sign_in\", expect.anything());\n\n // Let getSession resolve to avoid dangling promise\n await act(async () => {\n resolveGetSession({ data: { session: { user: fakeUser } } });\n });\n });\n\n it(\"shows toast again after sign-out then fresh sign-in\", async () => {\n mockGetSession.mockResolvedValue({ data: { session: { user: fakeUser } } });\n\n await act(async () => {\n render(\n \n \n \n );\n });\n\n mockTrackEvent.mockClear();\n\n // Simulate sign-out\n await act(async () => {\n authCallback(\"SIGNED_OUT\", null);\n });\n\n // Simulate fresh sign-in\n await act(async () => {\n authCallback(\"SIGNED_IN\", { user: fakeUser });\n });\n\n expect(screen.getByText(/Signed in as testuser/)).toBeInTheDocument();\n expect(mockTrackEvent).toHaveBeenCalledWith(\"sign_in\", { provider: \"github\" });\n });\n});\n" }, { "path": "src/components/layout/AuthContext.tsx", "content": "\"use client\";\n\nimport { createContext, useContext, useEffect, useState, useCallback, useRef, type ReactNode } from \"react\";\nimport { supabase } from \"@/lib/supabase\";\nimport { downloadAndMerge, scheduleUpload, flushPendingUpload, mergeFromRealtimePayload } from \"@/lib/sync\";\nimport { trackEvent } from \"@/lib/analytics\";\nimport type { User } from \"@supabase/supabase-js\";\n\ninterface AuthContextValue {\n user: User | null;\n loading: boolean;\n signIn: () => Promise;\n signOut: () => Promise;\n syncNow: () => void;\n syncVersion: number;\n}\n\nconst AuthContext = createContext({\n user: null,\n loading: true,\n signIn: async () => {},\n signOut: async () => {},\n syncNow: () => {},\n syncVersion: 0,\n});\n\nexport function AuthProvider({ children }: { children: ReactNode }) {\n const [user, setUser] = useState(null);\n const [loading, setLoading] = useState(true);\n const [syncVersion, setSyncVersion] = useState(0);\n const [toast, setToast] = useState<{ message: string; type: \"error\" | \"success\" } | null>(null);\n const [toastFading, setToastFading] = useState(false);\n const realtimeChannelRef = useRef | null>(null);\n const hasSessionRef = useRef(false);\n\n useEffect(() => {\n if (!toast) return;\n const fadeTimer = setTimeout(() => setToastFading(true), 3000);\n const removeTimer = setTimeout(() => { setToast(null); setToastFading(false); }, 3700);\n return () => { clearTimeout(fadeTimer); clearTimeout(removeTimer); };\n }, [toast]);\n\n // Subscribe to realtime changes when user is signed in\n useEffect(() => {\n if (!user) {\n // Clean up any existing subscription\n if (realtimeChannelRef.current) {\n supabase.removeChannel(realtimeChannelRef.current);\n realtimeChannelRef.current = null;\n }\n return;\n }\n\n const channel = supabase\n .channel(\"user_progress_sync\")\n .on(\n \"postgres_changes\",\n {\n event: \"UPDATE\",\n schema: \"public\",\n table: \"user_progress\",\n filter: `user_id=eq.${user.id}`,\n },\n (payload) => {\n const changed = mergeFromRealtimePayload(payload.new);\n if (changed) {\n trackEvent(\"realtime_sync\");\n setSyncVersion((v) => v + 1);\n }\n }\n )\n .subscribe();\n\n realtimeChannelRef.current = channel;\n\n return () => {\n supabase.removeChannel(channel);\n realtimeChannelRef.current = null;\n };\n }, [user]);\n\n useEffect(() => {\n // Next.js App Router clears the URL hash during hydration before\n // Supabase can detect it. We capture it early in an inline