Remove Duplicates from Sorted List II

From the leetcode exercise https://leetcode.com/explore/challenge/card/january-leetcoding-challenge-2021/579/week-1-january-1st-january-7th/3593/

Given the head of a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Return the linked list sorted as well.

Example 1:

Input: head = [1,2,3,3,4,4,5]
Output: [1,2,5]

Example 2:

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

Constraints:

• The number of nodes in the list is in the range [0, 300].
• -100 <= Node.val <= 100
• The list is guaranteed to be sorted in ascending order.

Solution

/**
 * 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) {
        ListNode prev=new ListNode(-101,head);
        ListNode result = prev;
        
        //iterate from begining to end
            //find repeated else go on
                //if found get next node after repeated
                //skip repeated
            
        while( head != null){
            if(head.next != null && head.val == head.next.val ){
                int value=head.val;  //1
                while(head != null && value == head.val){
                    head=head.next;
                }
                prev.next = head;
            }else{
                prev = head;
                head=head.next;
            }
}
        return result.next;
    }
}