class Solution {//Ｖ＋Ｅ Ｖ
public:
    bool canVisitAllRooms(vector<vector<int>>& room) {
        int countRoom = room.size();
        int remainingRoom = countRoom - 1 ;

        vector<char> canEnter(countRoom, 0);
        vector<int> roomToOpen;

        canEnter[0] = 1;
        roomToOpen.push_back(0);

        while (!roomToOpen.empty()) {
            int currentRoom = roomToOpen.back();

            roomToOpen.pop_back();
            for (int nextRoom : room[currentRoom]){
                if (!canEnter[nextRoom]) {
                    canEnter[nextRoom] = 1;
                    --remainingRoom;

                    if ( remainingRoom == 0)
                    return true;

                    roomToOpen.push_back(nextRoom);
                    }
                }
            }
        return remainingRoom == 0;
    }
};