面試最常問的陣列轉樹，樹轉陣列 c++ web框架paozhu實現

struct department_outjson_t
{
  unsigned int id          = 0;
  unsigned int parentid    = 0;
  bool isopen              = true;
  bool _is_use             = false;
  std::string title;
  std::string desc;
  std::vector<department_outjson_t> children;

};

template <typename deps_json_type>
concept ishas_isuse_member = requires(deps_json_type m) { m._is_use; };

template <typename deps_json_type>
  requires ishas_isuse_member<deps_json_type>
void array_to_tree(std::vector<deps_json_type> &targetdata,
                   std::vector<deps_json_type> &sourcedata)
{

  if (targetdata.size() == 0)
  {
    for (unsigned int i = 0; i < sourcedata.size(); i++)
    {
      if (sourcedata[i].parentid == 0)
      {
        targetdata.push_back(sourcedata[i]);
        sourcedata[i]._is_use = true;
      }
    }
  }

  for (unsigned int i = 0; i < sourcedata.size(); i++)
  {
    if (sourcedata[i]._is_use == false)
    {
      for (unsigned int j = 0; j < targetdata.size(); j++)
      {
        if (targetdata[j].id == sourcedata[i].parentid)
        {
          targetdata[j].children.push_back(sourcedata[i]);
          sourcedata[i]._is_use = true;
          array_to_tree(targetdata[j].children, sourcedata);
        }
      }
    }
  }
}

template <typename deps_json_type>
void tree_to_array(std::vector<deps_json_type> &targetdata,
                   std::vector<deps_json_type> &sourcedata,
                   unsigned int parendid = 0)
{

  for (unsigned int i = 0; i < sourcedata.size(); i++)
  {
    if (sourcedata[i].parentid == parendid)
    {
      if (sourcedata[i].children.size() > 0)
      {
        deps_json_type temp = sourcedata[i];
        temp.children.clear();
        targetdata.push_back(temp);
        tree_to_array(targetdata, sourcedata[i].children, sourcedata[i].id);
      }
      else
      {
        targetdata.push_back(sourcedata[i]);
      }
    }
  }
}