Duplicates Remove from Sorted List II leetcode Python

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


For example,

Given 1->2->3->3->4->4->5, return 1->2->5.

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

The practice is to use two pointers to the pre cur

1.dummy.next= Head

2.pre=dummy Cur=dummy,next

3. When the pointer moves to the Pre.next and Cur.next positions, add this position to the pre.next.

4. If no, skip cur.

One traversal time is O (n)

The code is as follows

# Definition for singly-linked list.# class listnode:#     def __init__ (self, x): #         self.val = x#         Self.next = Nonec Lass Solution:    # @param head, a listnode    # @return a listnode    def deleteduplicates (self, head):        if head== None or Head.next==none:            return head                    dummy=listnode (0)        dummy.next=head        pre=dummy        cur= Dummy.next while                Cur!=none: While            cur.next and cur.next.val==pre.next.val:                cur=cur.next            if Pre.next==cur:                pre=pre.next            Else:                pre.next=cur.next            cur=cur.next        return Dummy.next

Duplicates Remove from Sorted List II leetcode Python