链表_leetcode328

# 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
        """

        if not head or not head.next:
            return head

        head1 = ListNode(0)
        head2 = ListNode(0)
        p1 = head1
        p2 = head2

        odd = True

        cur = head

        while cur:

            if odd:
                p1.next = cur
                p1 = cur
                odd = False
            else:
                p2.next = cur
                p2 = cur
                odd = True

            cur = cur.next


        p1.next = head2.next
        p2.next = None
        
        return head1.next