/** * Definition for singly-linked list. * public class ListNode { *     public int val; *     public ListNode next; *     public ListNode(int x) { val = x; } * } */public class Solution {    public ListNode RemoveElements(ListNode head, int val) {        if (head == null)            {                return null;            }            else            {                var temp = head;                ListNode last = null;                while (temp != null)                {                    if (temp.val != val)                    {                        last = temp;                        temp = temp.next;                    }                    else                    {                        if (temp.next != null)                        {                            temp.val = temp.next.val;                            temp.next = temp.next.next;                        }                        else                        {                            if (last != null)                            {                                last.next = null;                            }                            break;                        }                    }                }                if (head.next != null && head.next.val == val)                {                    head.next = null;                }                if (head.val == val)                {                    head = null;                }                return head;            }    }}