private function populateAB(Category $category)
 {
     $aclass = array();
     $bclass = array();
     $topteams = $category->getTopteams();
     $groups = $category->getGroupsClassified(Group::$PRE);
     $g = 1;
     /* @var $group Group */
     foreach ($groups as $group) {
         $teams = count($group->getTeams());
         for ($i = $teams; $i > 0; $i--) {
             if ($i > $topteams) {
                 $bclass[$g][$i - $topteams] = "0:" . $g . "r" . $i;
             } else {
                 $aclass[$g][$i] = "0:" . $g . "r" . $i;
             }
         }
         $g++;
     }
     $astrategy = $this->unfoldStrategy($aclass, 'A');
     $bstrategy = $this->unfoldStrategy($bclass, 'B');
     return $this->populateQMatches($category, array_merge($bstrategy, $astrategy));
 }