Shortest Item-to-Item Travel Distance Across Pins

Question

### Interview Question: Compute Shortest Item-to-Item Travel Distance Across Pins You are given a list of pins, where each pin contains a list of items. An item may appear in multiple pins, but within any single pin it appears at most once. We define a graph implicitly like this: - Every item is a node. - If two items appear together inside the same pin, they have an edge of weight 1 between them. The **travel distance** between two items is the **shortest number of hops** between them through these edges. Distance rules: 1. Distance = 1 if the two items appear together in the same pin. 2. Distance = 2 if they can be connected via exactly one intermediate item. 3. Distance = k (any positive integer) if the shortest chain of item-to-item connections has length k. 4. Distance = -1 if no path exists. Your task: Given a list of pins and two target items, return their shortest travel distance. --- ### Concrete Example (Distance > 2) Pins: Pin 1: [A, B] Pin 2: [B, C] Pin 3: [C, D] Graph connections: A <-> B (Pin 1) B <-> C (Pin 2) C <-> D (Pin 3) Distances: distance(A, B) = 1 distance(A, C) = 2 (A -> B -> C) distance(A, D) = 3 (A -> B -> C -> D) --- ### More E

Accepted Answer

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