LeetCode 203. Remove Linked List Elements

简单的不能再简单了 但是第一次做的时候就是死心眼 认准了只用一个指针

class Solution {
    public ListNode removeElements(ListNode head, int val) {
        if (head == null) return null;
        
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode pre = dummy;
        ListNode cur = head;
        while (cur != null) {
            if (cur != null && cur.val == val) {
                pre.next = cur.next;
                cur = cur.next;
            } else {
                pre = pre.next;
                cur = cur.next;
            }
        }
        
        return dummy.next;
    }
}