public static ListNode deleteDuplicates(ListNode head) { if (head == null || head.next == null) { return head; } ListNode current = head; while (current.next != null) { if (current.val == current.next.val) { current.next = current.next.next; // 删除重复节点 } else { current = current.next; // 移动到下一个节点 } } return head; }