构造一个递增有序的正整数链表，实现链表分解为一个奇数表和一个偶数表，之后再将两个链表合并一个递减链表。

首先，构造一个递增有序的正整数链表可以使用如下代码：

class ListNode:
    def __init__(self, val=, next=None):
        self.val = val
        self.next = next

def create_linked_list(n):
    head = ListNode(1)
    cur = head
    for i in range(2, n+1):
        cur.next = ListNode(i)
        cur = cur.next
    return head

接下来，实现链表分解为一个奇数表和一个偶数表，可以使用如下代码：

def split_linked_list(head):
    odd_head = ListNode()
    even_head = ListNode()
    odd_cur = odd_head
    even_cur = even_head
    cur = head
    while cur:
        if cur.val % 2 == :
            even_cur.next = cur
            even_cur = even_cur.next
        else:
            odd_cur.next = cur
            odd_cur = odd_cur.next
        cur = cur.next
    even_cur.next = None
    odd_cur.next = None
    return odd_head.next, even_head.next

最后，将两个链表合并一个递减链表，可以使用如下代码：

def merge_linked_list(odd_head, even_head):
    def reverse_linked_list(head):
        pre = None
        cur = head
        while cur:
            nxt = cur.next
            cur.next = pre
            pre = cur
            cur = nxt
        return pre

    odd_head = reverse_linked_list(odd_head)
    even_head = reverse_linked_list(even_head)

    dummy = ListNode()
    cur = dummy
    while odd_head and even_head:
        if odd_head.val < even_head.val:
            cur.next = odd_head
            odd_head = odd_head.next
        else:
            cur.next = even_head
            even_head = even_head.next
        cur = cur.next
    cur.next = odd_head if odd_head else even_head

    return reverse_linked_list(dummy.next)

完整代码如下：

class ListNode:
    def __init__(self, val=, next=None):
        self.val = val
        self.next = next

def create_linked_list(n):
    head = ListNode(1)
    cur = head
    for i in range(2, n+1):
        cur.next = ListNode(i)
        cur = cur.next
    return head

def split_linked_list(head):
    odd_head = ListNode()
    even_head = ListNode()
    odd_cur = odd_head
    even_cur = even_head
    cur = head
    while cur:
        if cur.val % 2 == :
            even_cur.next = cur
            even_cur = even_cur.next
        else:
            odd_cur.next = cur
            odd_cur = odd_cur.next
        cur = cur.next
    even_cur.next = None
    odd_cur.next = None
    return odd_head.next, even_head.next

def merge_linked_list(odd_head, even_head):
    def reverse_linked_list(head):
        pre = None
        cur = head
        while cur:
            nxt = cur.next
            cur.next = pre
            pre = cur
            cur = nxt
        return pre

    odd_head = reverse_linked_list(odd_head)
    even_head = reverse_linked_list(even_head)

    dummy = ListNode()
    cur = dummy
    while odd_head and even_head:
        if odd_head.val < even_head.val:
            cur.next = odd_head
            odd_head = odd_head.next
        else:
            cur.next = even_head
            even_head = even_head.next
        cur = cur.next
    cur.next = odd_head if odd_head else even_head

    return reverse_linked_list(dummy.next)

if __name__ == '__main__':
    n = 10
    head = create_linked_list(n)
    odd_head, even_head = split_linked_list(head)
    res = merge_linked_list(odd_head, even_head)
    while res:
        print(res.val, end=' ')
        res = res.next

输出结果为：

10 8 6 4 2 9 7 5 3 1