leetcode刷题之路—— 删除排序链表中的重复元素

中文网leetcode第38题。
题目描述：

方法一：

 public ListNode deleteDuplicates(ListNode head) {
        ListNode cur = head.next;
        ListNode prev = head;
        while(cur != null){
            while(cur != null && cur.val == prev.val){
                cur = cur.next;
            }
            if(cur == null){
                prev.next = null;
                break;
            }
            prev.next = cur;
            prev = cur;
            cur = cur.next;
        }
        return head;
    }

方法二：

public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null) return head;
        deleteDuplicates(head.next);
        if(head.val == head.next.val) head = head.next;
        return head;
    }