3v4l.org

run code in 300+ PHP versions simultaneously
<?php function getTree($treeByParent, $treeByCat, $id, $listed = []) { $gTree = []; $gTree[] = $treeByCat[ $id ]; if ( count($treeByParent[ $id ]) > 0) { foreach ($treeByParent[ $id ] as $cat) $gTree[] = $cat; } if ( count($treeByParent[ $treeByCat[ $id ] ]) > 0 ) $gTree[] = getTree($treeByParent, $treeByCat, $treeByCat[ $id ]); return $gTree; } $treeByParent = array( 0 => array(1, 2), 1 => array(3, 7), 3 => array(4), 4 => array(5) ); $treeByCat = array( 1 => 0, 2 => 0, 3 => 1, 7 => 1, 4 => 3, 5 => 4 ); print_r( getTree($treeByParent, $treeByCat, 4) );

preferences:
31.42 ms | 402 KiB | 5 Q