Odd Even Linked List in Python
Suppose we have a singly linked list, we have to group all odd nodes together followed by the
even nodes. Here we are talking about the node position not the value in the nodes. We should
try to do it in place. So if the nodes are [1,22,13,14,25], the result will be [1,13,25,22,14]
To solve this, we will follow these steps −
if head is null or the next of head is null, then return head
head1 := head, head2 := next of head, head_beg := next of head
while next of head2 is nor null and next of (next of head is not null)
next of head1 := next of head2
next of head2 = next of (next of head)
head1 := next of head1 and head2 := next of head2
if next of head2 is not null
next of head1 := head2_beg and next of head2 = null
return head
Example
Let us see the following implementation to get better understanding −
class Solution(object):
def oddEvenList(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
if head == None or head.next ==None:
return head
head1=head
head2,head2_beg= head.next,head.next
while head2.next!= None and head2.next.next!= None:
head1.next = head2.next
head2.next = head2.next.next
head1 = head1.next
head2 = head2.next
if head2.next!=None:
head1.next = head2.next
head1 = head1.next
head1.next = head2_beg
head2.next = None
return head
Input
[1,22,13,14,25]
Output
[1,13,25,22,14]
Published on 05-Feb-2020 10:43:34
