LeetCode Java Solutions Starter

🚀 Quick Commands

Build the project:

./gradlew build

Run example tests:

./gradlew test

🏗 Project Structure

leetcode-java/
├── src/
│   ├── main/
│   │   └── java/org/leetcode/       # Solution implementations
│   └── test/
│       └── java/org/leetcode/       # Unit tests
├── build.gradle                     # Build configuration
├── gradle/
│   └── wrapper/                     # Gradle wrapper files
└── settings.gradle                  # Project settings

🧩 Adding New Solutions

Create package for your problem (e.g., "twosum"):

mkdir -p src/main/java/org/leetcode/twosum
mkdir -p src/test/java/org/leetcode/twosum

Implement your solution:

// src/main/java/org/leetcode/twosum/Solution.java
package org.leetcode.twosum;

import java.util.HashMap;
import java.util.Map;

public class Solution {
    public int[] twoSum(int[] nums, int target) {
        Map<Integer, Integer> numMap = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            int complement = target - nums[i];
            if (numMap.containsKey(complement)) {
                return new int[]{numMap.get(complement), i};
            }
            numMap.put(nums[i], i);
        }
        throw new IllegalArgumentException("No solution found");
    }
}

Create corresponding tests:

// src/test/java/org/leetcode/twosum/SolutionTest.java
package org.leetcode.twosum;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

public class SolutionTest {
    private final Solution solution = new Solution();

    @Test
    public void testTwoSumBasicCase() {
        int[] result = solution.twoSum(new int[]{2,7,11,15}, 9);
        assertArrayEquals(new int[]{0,1}, result);
    }

    @Test
    public void testNoSolution() {
        assertThrows(IllegalArgumentException.class, () -> {
            solution.twoSum(new int[]{2,7,11,15}, 100);
        });
    }
}

⚙️ Build Commands

Command	Description
./gradlew build	Build the project
./gradlew test	Run all tests
./gradlew clean	Clean build artifacts
./gradlew test --tests org.leetcode.*	Run specific test class

🛠️ IDE Setup

IntelliJ IDEA

1. File → Open → Select build.gradle
2. Import as Gradle project
3. Enable auto-import

VS Code

1. Install Java Extension Pack
2. Open project folder
3. Trust Gradle wrapper

🤝 Contributing

1. Fork the repository
2. Create a new branch:

git checkout -b feature/solution-for-problem-xyz

3. Add your solution with tests
4. Commit your changes:

git commit -m "Add solution for Problem XYZ"

5. Push to your fork:

git push origin feature/solution-for-problem-xyz

6. Create a Pull Request

📊 Example Problem Progress

Problem	Solution	Tests	Difficulty
Two Sum	✅	✅	Easy
Add Two Numbers	❌	❌	Medium
Longest Substring	❌	❌	Medium

📜 License

MIT License - See LICENSE for details.

🙌 Acknowledgments

• Inspired by LeetCode's problem set
• Built with Gradle and JUnit
• Community contributions welcome