Python：NameError：未定义全局名称“sortList”（递归期间）

Question

在l1 = sortList(head)递归行 ( ) 中，我得到NameError: global name 'sortList' is not defined. 谁能指出我哪里做错了？

class Solution:
    # @param head, a ListNode
    # @return a ListNode

    def sortList(self, head):
        if head == None or head.next == None:
            return head

        slow = head
        fast = head

        while fast != None and fast.next != None:
            slow = slow.next
            fast = fast.next.next
        fast = slow
        slow = slow.next
        fast.next = None
        l1 = sortList(head)
        l2 = sortList(slow)
        l = mergeTwoLists(l1, l2)
        return l

Answer 1

sortList是 的一种方法Solution，不是独立存在的。用：

self.sortList(head)

它会起作用。