Linked List Midpoint | Dataford Interview Questions

Tempus Labs processes ordered records represented as singly linked lists. Given the head of a singly linked list, return the value stored in its midpoint node.

Use the second middle node when the list has an even number of nodes. For example, the midpoint of 1 -> 2 -> 3 -> 4 is 3.

Formal Specification

Implement midpoint(head), where head is either None or a ListNode with:

val, an integer value
next, a reference to the next ListNode or None

Return the integer value of the midpoint node. The input list is non-empty. Do not modify the list, and do not convert it into another data structure.

Constraints

1 <= number of nodes <= 10^5
-10^9 <= node.val <= 10^9
The list contains no cycles
The input list must remain unchanged

Function Signature

def midpoint(head):

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