876.py

# Name: Middle of the Linked List
# Link: https://leetcode.com/problems/middle-of-the-linked-list/
# Method: Fast slow runner
# Time: O(n)
# Space: O(1)
# Difficulty: Easy


#  Definition for singly-linked list.
class ListNode:
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution:
    def middleNode(self, head: ListNode) -> ListNode:
        slowboie = head
        fastboye = head
        while fastboye != None:
            fastboye = fastboye.next
            if fastboye:
                slowboie = slowboie.next
                fastboye = fastboye.next
            else:
                break
        return slowboie.val


if __name__ == "__main__":
    sol = Solution()
    head = ListNode(3)
    head.next = ListNode(4)
    head.next.next = ListNode(5)
    head.next.next.next = ListNode(6)

    print(sol.middleNode(head))