PHP specified fields are more than 100 in positive order and less than 100 in random order

   $arr = [
           [
               'id'=>1,
               'name'=>'xiaonian',
               'time'=>111,
               'sort'=>100,
           ],
           [
               'id'=>2,
               'name'=>'xiaonian',
               'time'=>111,
               'sort'=>0,
           ],
           [
               'id'=>3,
               'name'=>'xiaogang',
               'time'=>111,
               'sort'=>0,
           ],
           [
               'id'=>4,
               'name'=>'xiaoming',
               'time'=>222,
               'sort'=>100,
           ],
           [
               'id'=>5,
               'name'=>'xiaoming',
               'time'=>222,
               'sort'=>0,
           ],
       ];

        usort($arr, function($a, $b) {
    
            $day['a'] =  $a['time'];
            $day['b'] = $b['time'];
            if ($day['a'] != $day['b']) {
    
                return strtotime($day['a']) - strtotime($day['b']);
            } else {
    
                if ($a['sort'] >= 100 && $b['sort'] >= 100) {
    
                    return $a['id'] - $b['id'];
                } elseif ($a['sort'] < 100 && $b['sort'] < 100) {
    
                    return pow(-1, rand(0,1));
                } else {
    
                    return $b['sort'] - $a['sort'];
                }
            }
        });