LeetCode Solutions

This repository contains my solutions to various LeetCode problems, organized by problem number.

Problems

#	Title	Difficulty	Solution	LeetCode Link
001	Two Sum	Easy	Python	Problem
002	Add Two Numbers	Medium	Python	Problem
003	Longest Substring Without Repeating Characters	Medium	Python	Problem
004	Median of Two Sorted Arrays	Hard	Python	Problem
005	Longest Palindromic Substring	Medium	Python	Problem
006	Zigzag Conversion	Medium	Python	Problem
007	Reverse Integer	Medium	Python	Problem
008	String to Integer (atoi)	Medium	Python	Problem
009	Palindrome Number	Easy	Python	Problem

Environment Setup

Prerequisites

• Python 3.8+ (Install from python.org or Microsoft Store)
• pip (Python package installer, included with Python)
• Visual Studio Code (recommended)

Setup Instructions for Windows

1. Install Python

Install Python from the official website or the Microsoft Store.

2. Verify Installation

Open Command Prompt and verify Python is installed:

python --version
pip --version

3. Clone this repository:

git clone https://github.com/yourusername/LeetCode.git
cd LeetCode

4. Set up a virtual environment

Using Command Prompt:

# Create a virtual environment
python -m venv .venv

# Activate the virtual environment
.venv\Scripts\activate

# Confirm you're using the virtual environment Python
where python

Using PowerShell:

# Create a virtual environment
python -m venv .venv

# Activate the virtual environment
.venv\Scripts\Activate.ps1

# If you get an execution policy error, you might need to run:
# Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope Process

Using Visual Studio Code:

• Open the project folder in VS Code
• Press Ctrl+Shift+P to open the command palette
• Type "Python: Select Interpreter" and select the virtual environment
• Open a new terminal (it will automatically activate the environment)

5. Install dependencies:

pip install pytest

6. Deactivate the virtual environment when done:

deactivate

Running Tests

Each solution has a corresponding test file in the test directory. To run tests:

Run all tests:

pytest

Run tests for a specific problem:

pytest test/test_001.py

Run tests with detailed output:

pytest -v

Run tests and display print statements:

pytest -s

Test File Structure

Test files follow this format:

# test/test_001.py
import pytest
import sys
import os
import importlib

# Add the parent directory to the Python path
sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

# Import the solution
solution_module = importlib.import_module("001_two_sum")
Solution = solution_module.Solution

class TestTwoSum:
    def setup_method(self):
        self.solution = Solution()
    
    def test_example_1(self):
        assert self.solution.twoSum([2, 7, 11, 15], 9) == [0, 1]

Resources

For each problem, you can find discussions and alternative approaches on the LeetCode discussion page, linked in the table above.

Notes

• Solutions are primarily written in Python
• Each solution includes comments explaining the approach and time/space complexity
• All solutions pass LeetCode's test cases