Reverse Nodes in k-groups leetcode Python

Given A linked list, reverse the nodes of a linked list K at a time and return its modified list.


If the number of nodes is not a multiple of k then left-out nodes in the end should remain as it is.


You may not alter the values in the nodes, and only nodes itself is changed.


Only constant memory is allowed.


For example,
Given this linked list:1->2->3->4->5


For k = 2, you should return:2->1->4->3->5

For k = 3, you should return:3->2->1->4->5

This approach is similar to reverse linklist and reverse pair, and requires a function to reverse.

The title means that every K node flips once, if not enough k to not turn.

# Definition for singly-linked list.# class listnode:# def __init__ (self, x): #  Self.val = x# Self.next = Noneclass Solution: # @param head, a ListNode # @param k, an integer # @return             A ListNode def reverse (self,start,end): Dummy=listnode (0) Dummy.next=start while Dummy.next!=end:        Tmp=start.next Start.next=tmp.next Tmp.next=dummy.next dummy.next=tmp        Return End,start def reversekgroup (self, head, K): If Head==none:return None dummy=listnode (0)                Dummy.next=head Start=dummy while start.next:end=start for I in Range (k-1): End=end.next if End.next==none:return dummy.next newstart,newend=                        Self.reverse (start.next,end.next) Start.next=newstart start=newend return Dummy.next 

Reverse Nodes in k-groups leetcode Python