链表排序 python

创建链表，并按奇偶分开，并排序

class ListNode(object):
    def __init__(self, val):
        self.val = val
        self.next = None
class Solution(object):
    def sortList(self, head):
        if not head or not head.next:
            return head
        pre, slow, fast = None, head, head
        #归并排序，找到中间部分
        while fast and fast.next:
            prev, slow, fast = slow, slow.next, fast.next.next
        prev.next = None #分为两部分
        l1 = self.sortList(head)
        l2 = self.sortList(slow)
        return self.merge(l1, l2)
    def merge(self, l1, l2):
        dummy = l = ListNode(None)
        while l1 and l2:
            if l1.val < l2.val:
                l.next, l, l1 = l1, l1, l1.next
            else:
                l.next, l, l2 = l2, l2, l2.next
        l.next = l1 if l1 else l2
        return dummy.next


if __name__ == "__main__":
    s = Solution()
    l = head = ListNode(None)
    for val in [0, 4, 1, 6, 7,9,8,7,1,5]:
        l.next = ListNode(val)
        l = l.next
    head = head.next
    li = s.sortList(head)
    while li:
        print(li.val, end=' ')
        li = li.next
    
    # 链表分为奇偶两部分并排序
    head1, head2 = ListNode(None),ListNode(None)
    p1, p2, p = head1, head2, head
    while p:
        if p.val % 2 == 1:
            p1.next = p
            p1 = p1.next
        else:
            p2.next = p
            p2 = p2.next
        p = p.next
    p1.next = None
    p2.next = None
    head1 = head1.next
    head2 = head2.next
    li1 = s.sortList(head1)
    print('\n')
    while li1:
        print(li1.val, end=' ')
        li1 = li1.next    
    li2 = s.sortList(head2)
    print('\n')
    while li2:
        print(li2.val, end=' ')
        li2 = li2.next