Odd Even Linked List

Problem: Odd Even Linked List

We can use two pointer to store odd linked list and even linked list separately. We can use another pointer to scan through the linked list and link current node to one of the two storing pointers in turn.

Code in Python:

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def oddEvenList(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        if not head: return head
        odd, even = ListNode(-1), ListNode(0)
        h1, h2 = odd, even
        switch = 1
        while head:
            if switch:
                odd.next, head, switch = head, head.next, 0
                odd = odd.next
            else:
                even.next, head, switch = head, head.next, 1
                even = even.next
        odd.next, even.next = h2.next, None
        return h1.next