Python: NameError: global name 'sortList' is not defined (During Recursion)

Question

In the line (l1 = sortList(head)) for recursion, I get NameError: global name 'sortList' is not defined. Could anyone point out where I did wrong?

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

Welcome to SO. I've edited your code a bit - usually displaying a more minimal coding example (not the entire code, but just the relevant part) helps with the readability of the question. — tktk
– tktk, Commented Jun 18, 2014 at 17:53
It's also generally a good practice to accept the answer that answered your question. — tktk
– tktk, Commented Jun 18, 2014 at 18:30
Should I accept an answer by voting up or other method? Since I just entered Stackoverflow and my reputation hasn't reached 15, I could not vote up currently. I will definitely do so after I can. Thanks again. — jasonccc
– jasonccc, Commented Jun 18, 2014 at 19:04
There's a green V mark under the voting. see here: stackoverflow.com/tour — tktk
– tktk, Commented Jun 18, 2014 at 19:37

tktk · Accepted Answer · 2014-06-18 17:49:42Z

10

sortList is a method of Solution, and doesn't exist independently. Use:

self.sortList(head)

and it would work.

answered Jun 18, 2014 at 17:49

tktk

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Comments

timgeb · Accepted Answer · 2014-06-18 17:56:33Z

1

Change l1 = sortList(head) to l1 = self.sortList(head), and l2 = sortList(slow) to l2 = self.sortList(slow). sortList is defined in the Solution class and does not exist globally, that's why you need self to refer to the current Solution object.

edited Jun 18, 2014 at 17:56

answered Jun 18, 2014 at 17:49

timgeb

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Comments

Alex · Accepted Answer · 2014-06-18 17:51:48Z

0

You have not imported any function named sortList, so there only exists a sortList that can be called on a Solution object.

Use self.sortList. self is a variable used in python to refer to the current object. Much like this in other languages.

answered Jun 18, 2014 at 17:51

Alex

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