Leetcode:26 — Remove Duplicates from sorted Array

Devhub

1 min readAug 22, 2025

Hey Folks. I am back with the classic Leetcode array problem.

Removing duplicates from a sorted Array.

For you reference I will attach the problem link here: https://leetcode.com/problem-list/nfkpb3yh/

It sounds simple when we read the question, but it is a little bit twisted if you have read the question completely.

We don’t directly remove the elements we rearrange them.

Let’s say we have an array [1,1,2,2,3,3,4]

the resultant array should be [1,2,3,4,_,_,_] remember the “_” is just for understanding the requirement we don’t have to replace the elements with “_”.

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So here I went with a classic two pointer approach

## Approach:
 - Here we go with a simple two pointer approach
 - we initialize two pointer i and j and another value to track the last updated index
 - we compare the array elements with the index
 - when we encounter the different elements we got the unique one
 - so we just shift the element at index j to the index of last updated index

public static int getTheUniques(int[] arr){
        int i=0, j=1, lastUpdated =1;

        while(j<arr.length){
            if(arr[i] != arr[j]){
                arr[lastUpdated]=arr[j];
                i = j;
                j++;
                lastUpdated++;
            }else{
                j++;
            }
        }
        for(int k=0;k<lastUpdated;k++){
            System.out.print(arr[k]+" "); // just to understand the execution
        }
        return lastUpdated;
    }