Reorder Two Linked Lists | Dataford Interview Questions

How would you reorder two linked lists by alternating nodes from each list, and then write unit tests?

Implement reorder_lists(head1, head2) using a ListNode structure with value and next fields. Return one in-place list starting with head1, alternating nodes while either list has remaining nodes. Unit tests should compare the resulting values and cover equal lengths, unequal lengths, empty inputs, and singleton lists.

Constraints

Each input is either None or the head of a singly linked list.
0 <= length(head1), length(head2) <= 100000
Node values are integers in the range -10^9 to 10^9.
Input lists contain no cycles.
Reuse the existing nodes and do not allocate nodes for the result.

Function Signature

def reorder_lists(head1, head2):

Your question is Reorder Two Linked Lists. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

How would you reorder two linked lists by alternating nodes from each list, and then write unit tests?

Constraints

Each input is either None or the head of a singly linked list.
0 <= length(head1), length(head2) <= 100000
Node values are integers in the range -10^9 to 10^9.
Input lists contain no cycles.
Reuse the existing nodes and do not allocate nodes for the result.

Function Signature

def reorder_lists(head1, head2):

Your question is Reorder Two Linked Lists. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.