题目简述

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.

解题思路

# Definition for singly-linked list.

# class ListNode:

#     def __init__(self, x):

#         self.val = x

#         self.next = None

class Solution:

    # @param head, a ListNode

    # @return a ListNode

    def deleteDuplicates(self, head):

        if head == None:

            return head

        pre = ListNode(-1)

        p = ListNode(-1)

        p = pre = head

        while p != None:

            if p.val == pre.val:

                if p.next == None:

                    pre.next = None

                else:

                    pre.next = p.next

                p = pre.next

            else:

                p = p.next

                pre = pre.next

        return head