Check Connectivity Between Two Subway Stations

You are given a New York subway network with stations (A, B, C, D, E, ...) and connectivity information: for each station, which other stations it connects to (an adjacency list). Implement a function isConnected(start, end) that returns whether two given stations start and end are connected, i.e., whether there exists a path from start to end. Notes: Stations may be represented as strings or integers. Typically, “connected” implies an undirected graph; if the interviewer specifies directed edges, treat it as directed reachability. Input A graph adjacency list: graph[station] = [neighbor1, neighbor2, ...] Two stations: start, end Output true/false: whether a path exists from start to end Typical constraints 1 <= V <= 1e5 0 <= E <= 2e5 Sample tests (5) Edges: A-B, B-C, query A -> C → true Edges: A-B, C-D, query A -> D → false Single node A, query A -> A → true Cycle A-B, B-C, C-A, query B -> A → true Chain A-B, B-C, C-D, D-E, query A -> E → true Example Input 3 A B B C C A C Output true