day8.py

# Recurse downwards with helper function, counting the number of nodes as you go
# Go back up the call stack, when you're at the middle, return the node.

class Solution:
    def middleNode(self, head: ListNode) -> ListNode:
        
        def helper(head, count):
            if not head: 
                return count
            rest = helper(head.next, count + 1)
                
            # int(rest / 2) + (rest % 2 > 0) == math.ciel(rest/2)
            if type(rest) == int and count == int(rest / 2) + (rest % 2 > 0):
                return head
            else:
                return rest
        
        return helper(head, 1)