# 83. Remove Duplicates from Sorted List

Given a sorted linked list, delete all duplicates such that each element appear only _once_.

**Example 1:**

```
Input: 1->1->2
Output: 1->2
```

**Example 2:**

```
Input: 1->1->2->3->3
Output: 1->2->3
```

#### 解题要点：

使用递归，找出当前节点和后一个节点是否一样，如一样，直接删除当前节点，指向下一节点。

```java
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null) return head;
        head.next = deleteDuplicates(head.next);
        return head.val == head.next.val ? head.next : head;
    }
}
```
