841. Keys and Rooms - LeetCode Solution

class Solution:
    def canVisitAllRooms(self, rooms: List[List[int]]) -> bool:
        visited = {}
        
        
        def dfs(node):
            if node in visited:
                return 
            visited[node] = 1
            
            for i in range(len(rooms[node])):
                dfs(rooms[node][i])
        dfs(0)
        return len(visited) == len(rooms)