Online PHP editor | refs for s8OLS

<?php function buildTreeHelper(&$array, $currentLevel = 1) { $result = array(); $lastIndex = 0; while($pair = each($array)) { list(, $row) = $pair; $level = $row['level']; if ($level > $currentLevel) { $result[$lastIndex]['children'] = buildTreeHelper($array, $level); } else if ($level == $currentLevel) { $result[++$lastIndex] = $row; } else { prev($array); // shift back break; } } return $result; } function buildTree($array) { reset($array); return buildTreeHelper($array); } $array = [ ['level'=>1, 'name' => 'Root #1'], ['level'=>1, 'name' => 'Root #2'], ['level'=>2, 'name' => 'subroot 2-1'], ['level'=>3, 'name' => '__subroot 2-1/1'], ['level'=>3, 'name' => '__subroot 2-1/2'], ['level'=>4, 'name' => '__subroot 2-2/1'], ['level'=>2, 'name' => 'subroot 2-2'], ['level'=>2, 'name' => 'subroot 2-3'], ['level'=>1, 'name' => 'Root #3'] ]; $time = microtime(true); var_dump(buildTree($array)); echo round(microtime(true) - $time, 10);