203. Remove Linked List Elements

Remove all elements from a linked list of integers that have value val.

Example

Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6

Return: 1 --> 2 --> 3 --> 4 --> 5

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode removeElements(ListNode head, int val) {
        ListNode dummy = new ListNode(val - 1);

        dummy.next =head;
        head = dummy;
        // if head.next is the val, remove it, don't update head, continue to check new next.
        // otherwise udpate it.
        while(head.next != null){
            if(head.next.val == val){
                head.next = head.next.next;
            }else
                head = head.next;
        }

        return dummy.next;
    }
}