LeetCode - Remove Duplicates from Sorted List | Darren's Blog

Given a sorted linked list, delete all duplicates such that each element appear only once.
For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

public ListNode deleteDuplicates(ListNode head) {

        if (head == null || head.next == null)  // No node or only a single node

            return head;

 

        ListNode previous = head, current = head.next;

 

        // Remove the current node if its value is the same with its previous node

        while (current != null) {

            if (current.val == previous.val) {  // Duplicates found

                previous.next = current.next;

                current = current.next;

            } else {    // Move to the next node

                previous = current;

                current = current.next;

            }

        }

 

        return head;

    }

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