Find Duplicates in an Array (Java)

Welcome to the repository for solving a common coding interview problem: Finding duplicates in an array using Java! 🚀

This repository contains a simple yet efficient solution to identify duplicate elements in an array, explained step-by-step with clean, optimized code.

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Problem Statement

Given an array of integers, find all elements that occur more than once. If no duplicates exist, return an empty list.

Example:

Input: [4, 3, 2, 7, 8, 2, 3, 1]
Output: [2, 3]

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Solution Overview

This solution leverages:

• HashSet: To track seen elements efficiently.
• ArrayList: To store duplicate elements.

The algorithm is efficient, with a time complexity of O(n) and space complexity of O(n).

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Code

Here’s the implementation:

import java.util.*;

class Solution {
    public List<Integer> findDuplicates(int[] arr) {
        List<Integer> result = new ArrayList<>();
        Set<Integer> seen = new HashSet<>();
        
        for (int num : arr) {
            if (!seen.add(num)) {
                result.add(num);
            }
        }
        
        return result;
    }
}

How to Run the Code

1. Clone this repository to your local machine:

git clone https://github.com/yourusername/find-duplicates-in-array-java.git
cd find-duplicates-in-array-java

2. Compile the code:

javac Solution.java

3. Run the program with an example input:

java Solution

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Watch the Video Explanation 🎥

For a detailed, step-by-step walkthrough of the code, watch my YouTube video: 🔗 Java Coding Tutorial: Find Duplicates in an Array - https://youtu.be/ukuKhemNH3g

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Contributing

If you have any improvements or suggestions, feel free to fork the repo and create a pull request. Contributions are always welcome! 🙌

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Contact

If you have questions or want to collaborate, feel free to connect with me: 📧 Email: rahulvijayan2291@gmail.com 🔗 LinkedIn: https://www.linkedin.com/in/rahul-vijayan-682a12194/ 🌟 Don’t forget to star this repository if you found it helpful!

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License

This project is licensed under the MIT License - see the LICENSE file for details.