Interactive Story Endings Reachability (Choices/Options)

You are given a simplified interactive-story model: choices: a list of choice records. Each record has the form choice = [start, op1, op2], meaning that from node start you can pick one of two options: op1 or op2. options: a mapping describing where each option op leads (i.e., the next node). endingList: a list of ending node IDs. Implement a function that determines which ending nodes in endingList are reachable from a given startNode, assuming the player can repeatedly pick either option at each step. Requirements: Reachability may require multiple hops. Cycles may exist; avoid infinite loops. During the interview, clearly state your chosen input representation (e.g., options as a dict op -> nextNode) and provide a runnable implementation. Constraints (you may state reasonable ones): e.g., |choices|, |options| <= 2e5. Example (illustrative): choices: [[1, "A", "B"], [2, "C", "D"], ...] options: { "A": 2, "B": 3, "C": 4, "D": 5 } endingList: [4, 5] startNode: 1 Output: [4, 5]. Example Input choices=[[1,"A","B"],[2,"C","D"],[3,"E","F"]] options={"A":2,"B":3,"C":4,"D":5,"E":6,"F":7} endingList=[4,5,7] startNode=1 Output [4,5,7] (order can vary)