Python describe LeetCode 82. Delete duplicate elements from the sort list II

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subject

Given the header of a sorted linked list head , Delete all nodes with duplicate numbers in the original linked list , Leave only different numbers . return Sorted linked list .

Example 1：

 Input ：head = [1,2,3,3,4,4,5]
Output ：[1,2,5]

Example 2：

 Input ：head = [1,1,1,2,3]
Output ：[2,3]

Tips ：

• The number of nodes in the linked list is in the range [0, 300] Inside
• -100 <= Node.val <= 100
• The title data ensures that the linked list has been in ascending order array

Python describe

Double pointer , Find nodes without duplicates

# Definition for singly-linked list.
# class ListNode:
# def __init__(self, val=0, next=None):
# self.val = val
# self.next = next
class Solution:
def deleteDuplicates(self, head: ListNode) -> ListNode:
th = ListNode(-1,head)
p,q = th,th
while q:
q = q.next
nc = 0
while q and q.next and q.next.val == q.val:
q = q.next
nc += 1
if nc == 0:
p.next = q
p = p.next
return th.next