LeetCode 841 Keys and Rooms - Mapping

Each room is a vertex, and each key in a room creates a directed edge to another room. Room $0$ has keys [1, 3] means edges $0 \to 1$ and $0 \to 3$.

You start in room $0$, so that is your source vertex. Run DFS to see which rooms you can reach. If you visit all $n$ rooms, return true.

This translation makes the problem trivial. It is a standard "can I reach all vertices from the source?" question.