203. Remove Linked List Elements

递归

class Solution {
    public ListNode removeElements(ListNode head, int val) {
        if (head == null) {
            return null;
        }

        head.next = removeElements(head.next, val);
        return head.val == val ? head.next : head;
    }
}

迭代

class Solution {
    public ListNode removeElements(ListNode head, int val) {
        ListNode dummyHead = new ListNode(-1, head);
        ListNode curr = dummyHead;
        while (curr.next != null) {
            if (curr.next.val == val) {
                curr.next = curr.next.next;
            } else {
                curr = curr.next;
            }
        }

        return dummyHead.next;
    }
}

Reference

203. Remove Linked List Elements