middle-of-the-linked-list.py

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution(object):
    def middleNode(self, head):
        """
        :type head: Optional[ListNode]
        :rtype: Optional[ListNode]
        """

        count = 0
        curr_head = head
        
        while curr_head is not None:
            count+=1
            curr_head = curr_head.next
        
        if count == 1:
            start_idx = 1
        
        elif (count % 2 == 0):
            start_idx = (count/2) + 1
        
        else:
            start_idx = ((count-1)/2)+1
        
        curr_head = head
        middle_list = None
        count = 0
        
        while curr_head is not None:
            count+=1
            if count == start_idx:
                middle_list = curr_head
                break
            curr_head = curr_head.next
        
        return middle_list