Leetcode 0876 Middle of the Linked List

Problem statement

https://leetcode.com/problems/middle-of-the-linked-list/

Solution

Use two pointers: slow and fast, when fast will reach the end, slow one will be in the middle of list.

Complexity

Time complexity is O(n) ~ 1.5n, space complexity is O(1).

Code

class Solution:
    def middleNode(self, head):
        slow = head
        fast = head

        while fast and fast.next:
            slow = slow.next
            fast = fast.next.next
        return slow