43.II 841. Keys and Rooms

class Solution {
    public boolean canVisitAllRooms(List<List<Integer>> rooms) {
        boolean visitedRoom[]= new boolean[rooms.size()];
        Queue<Integer> queue = new LinkedList<Integer>();
        visitedRoom[0] = true; //first room alwasys visited

        for(int i=0;i<rooms.get(0).size();i++){
            queue.add(rooms.get(0).get(i));
        }

        while(!queue.isEmpty()){
            int key = queue.poll();
            visitedRoom[key]= true; //mark room is visted if key is present for that room

            for(int room : rooms.get(key)){
                //if room is not visited then we will add that key in our queue otherwise not required
                if(!visitedRoom[room]){
                    queue.add(room);
                }
            }
        }

        //now we will check room visited or not
        for(boolean b: visitedRoom){
            if(!b)return false;
        }
        return true;
        
    }
}