leetcode 【 Remove Duplicates from Sorted List 】 python 实现

题目：

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

.

代码：

# 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 is None or head.next is None:
return head

dummyhead = ListNode(0)
dummyhead.next = head
p = dummyhead.next

while p.next is not None:
if p.val == p.next.val:
p.next = p.next.next
else:
p = p.next

return dummyhead.next

思路：

设立虚表头dummyhead

遇上val不同的，再执行 p=p.next；否则指针p不动，只是p.next变化。