LeetCode Card 248 — Linked List / Structure
Pattern signal
This pattern usually appears when the prompt involves pointer rewiring, node-by-node traversal, or in-place reordering without random access. Reverse Linked List, Merge Two Lists, Reorder List, and remove-nth-from-end are standard representatives.
What Structure means here
In BASIC, the Structure step is where you state the invariant, helper contract, or control-flow skeleton before coding. For Linked List, that matters because the pattern only becomes useful once the candidate is explicit about what is being tracked, reduced, or preserved.
Interview move
A strong move is to make the plan visible before full execution. In this pattern family, say out loud what representation makes the problem easier: the map entry, the pointer invariant, the recursion contract, the queue contents, or the DP state. That keeps the implementation attached to a reason.
Common miss
The common failure is losing node references because the pointer update order was not planned first. BASIC reduces that risk because the stage sequence forces you to earn the implementation instead of jumping straight into it.
BASIC prompt
“Given that this looks like Linked List, what is the simplest way to state the invariant, helper contract, or control-flow skeleton before coding?”