Feedonomics Senior Full Stack Software Engineer interview questions

Guys most of the questions are above, here I'm gonna share the question I failed, as I promised the interviewer that I'm gonna solve it, I just needed more time. The most difficult question is the following: we have this array: $input = [ 'item/id' => 'my_id', 'item/title' => 'my_title', 'item/group1/val1' => 'my_val1', 'item/group1/val2' => 'my_val2', 'summary' => 'xyz', 'item/group1/val3' => 'my_val3', ]; We need to convert it to : Array ( [item] => Array ( [id] => my_id [title] => my_title [group1] => Array ( [val1] => my_val1 [val2] => my_val2 [val3] => my_val3 ) ) [summary] => xyz ) This is using PHP.