dgraph_dfs.cc

// TODO: Write a comment here.
void Dgraph::Dfs(int vertex) {
  auto *has_been_visited = new bool[this->vertices_];
  // set them all to unvisited.
  for (int index = 0; index < this->vertices_; index++) {
    has_been_visited[index] = false;
  }

  has_been_visited[vertex] = true;
  stack<int> stack;
  stack.push(vertex);

  cout << vertex << " ";

  while(!stack.empty()) {
    int *index = nullptr;

    list<int>::iterator iterator;
    for (iterator = this->list_[stack.top()].begin();
        iterator != this->list_[stack.top()].end();
        iterator++) {
      if (!has_been_visited[*iterator] && index == nullptr) {
        index = &*iterator;
      }
    }

    if (index == nullptr) {
      stack.pop(); // No such vertex available.
    } else {
      has_been_visited[*index] = true;
      cout << *index << " ";
      stack.push(*index);
    }

    index = nullptr;
  }

  delete[] has_been_visited;
}