841.cpp

class Solution {
public:
    bool canVisitAllRooms(vector<vector<int>>& rooms) {
        int numrooms = rooms.size();
        vector<bool> visited(numrooms, false);
        bool res = false;
        visited = dfs(rooms, 0, visited);
        for(int i = 0; i < numrooms; i++) {
            if (!visited[i]) return false;
        }
        return true;
    }
    vector<bool> dfs(vector<vector<int>>& rooms, int room, vector<bool> visited) {
        visited[room] = true;
        for(int nextroom : rooms[room]) {
            if (visited[nextroom] == false) visited = dfs(rooms, nextroom, visited);
        }
        return visited;
    }
};