remove duplicates from an unsorted array in java

Question

I was asked in one of the interview that i recently appeared to remove duplicates from unsorted array while still maintaining the order in which they appeared.

For example:

Input: int[] nums = [2,1,3,3,2,1,4]
Output shud be int[] result = [2,1,3,4]

I tried two options one with Hashset and other with list. But i was still wondering if there is an better optimized solution to this. Appreciate if you can help me out NerdyHB

Here is are solution

public static void main(String[] args) {
    int[] nums = new int[] { 2, 1, 3, 2, 1 };
    List<Integer> result = removeDuplicates(nums);
    System.out.println(result);

    int[] res = removeDuplicatesUsingHashSet(nums);
    System.out.println(Arrays.toString(res));
}

public static List<Integer> removeDuplicates(int[] nums) {
    List<Integer> result = new ArrayList<>();
    for (int n : nums) {
        if (!result.contains(n)) {
            result.add(n);
        }

    }
    return result;
}


public static int[] removeDuplicatesUsingHashSet(int[] nums) {
    HashSet<Integer> hset = new HashSet<>();
    for (int n : nums) {
        hset.add(n);
    }
    int[] result = new int[hset.size()];
    int counter = 0;
    Iterator<Integer> itr = hset.iterator();
    while (itr.hasNext()) {
        result[counter++] = itr.next();
    }

    return result;
}

your HashSet solution doesn't preserve order.

jdigital
– jdigital

2018-08-31 03:56:16 +00:00
Commented Aug 31, 2018 at 3:56 — jdigital
– jdigital, Commented Aug 31, 2018 at 3:56

Nerdy Bunz · Accepted Answer · 2018-08-31 04:02:40Z

1

Change the line:

HashSet<Integer> hset = new HashSet<>();

to:

LinkedHashSet<Integer> hset = new LinkedHashSet<>();

answered Aug 31, 2018 at 4:02

Nerdy Bunz

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Comments

Messi · Accepted Answer · 2019-05-06 05:42:40Z

0

import java.util.Arrays;
public class Main
{
public static void main (String[]args)
{
int[] arr = { 25, 14, 56, 15, 36, 36, 77, 18, 18, 49 };
int size=arr.length;
for(int i=0;i<size;i++)
{
  for(int j=i+1;j<size;j++)
  {
    if(arr[i]==arr[j])
    {
      arr[j]=arr[size-1];
      size--;
    }
 }
  }

 for(int a=0;a<size;a++)
  {
  System.out.print(arr[a]+" ");
  }

 }

}

answered May 6, 2019 at 5:42

Messi

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