LeetCode 841 Keys and Rooms - Problem Statement

you apply DFS immediately. Problem: Keys and Rooms (LeetCode $841$). You start in room $0$. Each room contains keys to other rooms. A key with number $k$ opens room $k$. Can you visit every room?

This is a reachability problem. Model it as a directed graph where each room is a vertex and each key creates an edge. Run DFS from room $0$. If you can reach all rooms, return true. Otherwise false. The graph is already given as an adjacency list (rooms array where rooms[i] contains keys in room i).