题目：

题解：

class Solution:
    def oddEvenList(self, head: ListNode) -> ListNode:
        if not head:
            return head
        
        evenHead = head.next
        odd, even = head, evenHead
        while even and even.next:
            odd.next = even.next
            odd = odd.next
            even.next = odd.next
            even = even.next
        odd.next = evenHead
        return head