Remove Duplicates from Sorted Linked List - The Coding Shala

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 In this post, we will learn how to Remove Duplicates from Sorted Linked List in Java.

Remove Duplicates from Sorted Linked List Problem

Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.

Example 1:

Input: head = [1,1,2]

Output: [1,2]

Example 2:

Input: head = [1,1,2,3,3]

Output: [1,2,3]

Remove Duplicates from Sorted Linked List Java Solution

Approach 1

Iterative method.

Time Complexity: O(n)
Space Complexity: O(1)

Java Program: 

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head == null) return head;
        
        ListNode current = head;
        
        while(current.next != null) {
            
            //check for duplicates
            if(current.val == current.next.val) {
                //if duplicate then skip next
                current.next = current.next.next;
            } else {
                current = current.next;
            }
            
        }
        return head;
    }
}

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