Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

Example 1:

Input: 1->2->3->3->4->4->5
Output: 1->2->5

Example 2:

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

LeetCode：連結

和劍指Offer_程式設計題56：刪除連結串列中重複的結點是一道題。

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if not head:
            return None
        phead = head
        pcur = None
        while phead:
            if phead.next and phead.val == phead.next.val:
                pnext = phead.next
                while pnext.next and pnext.next.val == phead.val:
                    pnext = pnext.next
                if phead == head:
                    head = pnext.next
                else:
                    pcur.next = pnext.next             
                phead = pnext.next
            else:
                pcur = phead
                phead = phead.next
        return head