Graph.cpp

bool Graph::dfs_util(int v, int *colors) {
  colors[v] = GRAY;

  for (auto *u : n_map[v]->adj) {
    if (colors[u->name] == GRAY) {
      return true;
    } else if (colors[u->name] == WHITE && dfs_util(u->name, colors)) {
      return true;
    }
  }

  colors[v] = BLACK;
  return false;
}

bool Graph::has_cycle() {
  int *colors = new int[n_map.size()];

  for (int i = 0; i < n_map.size(); i++) {
    colors[i] = WHITE;
  }

  for (int i = 0; i < n_map.size(); i++) {
    if (colors[i] == WHITE && dfs_util(i, colors)) {
      return true;
    }
  }

  return false;
}