LeetCode#83 Remove Duplicates from Sorted List

Problem Definition：

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

For example,
Given 1->1->2, return 1->2.
Given 1->1->2->3->3, return 1->2->3.

Solution : 值得注意的是递归解法：

 def deleteDuplicates(head):
        if head==None or head.next==None:
            return head
        head.next=self.deleteDuplicates(head.next)
        return head.next if head.val==head.next.val else head