Related Articles

# Remove duplicates from unsorted array using Set data structure

• Difficulty Level : Easy
• Last Updated : 03 Sep, 2021

Given an unsorted array of integers, print the array after removing the duplicate elements from it. We need to print distinct array elements according to their first occurrence.

Examples:

```Input: arr[] = { 1, 2, 5, 1, 7, 2, 4, 2}
Output: 1 2 5 7 4
Explanation: {1, 2} appear more than one time.

Input: arr[] = { 3, 3, 4, 1, 1}
Output: 3 4 1```

Approach:

• Take a Set
• Insert all array element in the Set. Set does not allow duplicates and sets like LinkedHashSet maintains the order of insertion so it will remove duplicates and elements will be printed in the same order in which it is inserted.
• Convert the formed set into array.
• Print elements of Set.

Below is the implementation of the above approach:

## C++

 `// CPP program to remove duplicates``// from unsorted array``#include ``using` `namespace` `std;` `// Function to remove duplicate from array``void` `removeDuplicates(``int` `arr[], ``int` `n)``{``    ``unordered_set<``int``> s;` `    ``// adding elements to LinkedHashSet``    ``for` `(``int` `i = 0; i < n; i++)``        ``s.insert(arr[i]);` `    ``// Print the elements of LinkedHashSet``    ``cout << ``"[ "``;``    ``for` `(``auto` `x : s)``        ``cout << x << ``" "``;``    ``cout << ``"]"``;``}` `// Driver code``int` `main()``{``    ``int` `arr[] = { 1, 2, 5, 1, 7, 2, 4, 2 };``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr);``  ` `    ``// Function call``    ``removeDuplicates(arr, n);``}` `// This code is contributed``// by Surendra_Gangwar`

## Java

 `// Java program to remove duplicates``// from unsorted array` `import` `java.util.*;` `class` `GFG {` `    ``// Function to remove duplicate from array``    ``public` `static` `void` `removeDuplicates(``int``[] arr)``    ``{``        ``LinkedHashSet set``            ``= ``new` `LinkedHashSet();` `        ``// adding elements to LinkedHashSet``        ``for` `(``int` `i = ``0``; i < arr.length; i++)``            ``set.add(arr[i]);` `        ``// Print the elements of LinkedHashSet``        ``System.out.print(set);``    ``}` `    ``// Driver code``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `arr[] = { ``1``, ``2``, ``5``, ``1``, ``7``, ``2``, ``4``, ``2` `};``      ` `        ``// Function call``        ``removeDuplicates(arr);``    ``}``}`

## Python3

 `# Python3 program to remove duplicates``def` `removeDulipcates(arr):``  ` `    ``# convert the arr into set and then into list``    ``return` `list``(``set``(arr))`  `# Driver Code``arr ``=` `[``1``, ``2``, ``5``, ``1``, ``7``, ``2``, ``4``, ``2``]` `# Function call``print``(removeDulipcates(arr))` `# This code is contributed``# by Mohit Kumar`

## C#

 `// C# program to remove duplicates``// from unsorted array``using` `System;``using` `System.Collections.Generic;` `class` `GFG``{``    ``// Function to remove duplicate from array``    ``public` `static` `void` `removeDuplicates(``int``[] arr)``    ``{``        ``HashSet<``int``> ``set` `= ``new` `HashSet<``int``>();` `        ``// adding elements to LinkedHashSet``        ``for` `(``int` `i = 0; i < arr.Length; i++)``            ``set``.Add(arr[i]);` `        ``// Print the elements of HashSet``        ``foreach``(``int` `item ``in` `set``) Console.Write(item + ``", "``);``    ``}` `    ``// Driver code``    ``public` `static` `void` `Main(String[] args)``    ``{``        ``int``[] arr = { 1, 2, 5, 1, 7, 2, 4, 2 };``      ` `        ``// Function call``        ``removeDuplicates(arr);``    ``}``}` `// This code is contributed by 29AjayKumar`

## Javascript

 ``
Output

`[ 4 7 5 1 2 ]`

Time Complexity: O(N)

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

My Personal Notes arrow_drop_up