Например так. Задать массив, описывающий подходящие индексы и соответствующие им размеры, искать подходящий индекс через array_search и заполнять нужные переменные:
$img_width = '';
$img_height = '';
$grid_num = '';
$settings = array(
array(
'indexes' => array(2, 4, 5, 11, 13, 14, 15, 16, 20, 21, 23, 24, 25, 27, 28, 31, 32, 35, 36, 38, 39, 41),
'img_width' => 100,
'img_height' => 100,
'grid_num' => 1
),
array(
'indexes' => array(1, 3, 7, 8, 9, 10, 12, 17, 19, 22, 26, 29, 30, 34, 37, 42),
'img_width' => 400,
'img_height' => 500,
'grid_num' => 2
),
array(
'indexes' => array(6, 18, 33, 40),
'img_width' => 430,
'img_height' => 240,
'grid_num' => 3
)
);
foreach ($settings as $setting) {
if (array_search($count_block, $setting['indexes']) !== false) {
$img_width = $setting['img_width'];
$img_height = $setting['img_height'];
$grid_num = $setting['grid_num'];
break;
}
}
