Doubly Linked List to Array

Given a non-null node from a doubly linked list (which might not be the head), return an array of values from head to tail.

1def to_array(node: 'DoublyNode') -> list[int]:
2    cur = node
3    while cur.prev:
4        cur = cur.prev
5    res = []
6    while cur:
7        res.append(cur.val)
8        cur = cur.next
9    return res

Linked List Copy

Linked List Midpoint

cur

action=move prev

Step 1 / 3

Step 1:

Walk backwards to find the head.

Pointers: cur=2

Focus: select @ [2]

action="move prev"