converting plain array to multidimensional one using recursion - php

Question

everyone!
I'm stuck trying write a recursive function. =(
This is my function, which, as I expected, will turn my plain array into multidimensional one.
function BuildTree($src, $index=0) {
foreach ($src as $index=>$curentItem) {
$nextItem = (is_array($src[$index+1]))?$src[$index+1]:false;
unset($src[$index]);
if ($nextItem['d']==$curentItem['d']) $brunchArray[] = $curentItem['n'];
if ($nextItem['d']>$curentItem['d']) $brunchArray['childrens'] = BuildTree($src, $index);
if (!$nextItem || $nextItem['d']<$curentItem['d']) return $brunchArray;
}
}
Input array is something like this:
$input = array (
array(
'n' => 'Articles',
'd' => 0
),
array(
'n' => 'Article 1',
'd' => 1
),
array(
'n' => 'Books',
'd' => 0
),
array(
'n' => 'Book 1',
'd' => 1
),
array(
'n' => 'Book 2',
'd' => 1
),
array(
'n' => 'Chapter 1',
'd' => 2
),
array(
'n' => 'Chapter 2',
'd' => 2
)
);
And I want it to be converted into this:
array (
array(
'n' => 'Articles',
'd' => 0,
'childrens' => array (
array(
'n' => 'Article 1',
'd' => 1
),
)
),
array(
'n' => 'Books',
'd' => 0,
'childrens' => array (
array(
'n' => 'Book 1',
'd' => 1
),
array(
'n' => 'Book 2',
'd' => 1
'childrens' => array (
array(
'n' => 'Chapter 1',
'd' => 2
),
array(
'n' => 'Chapter 2',
'd' => 2
)
)
)
)
)
)
I already spent three hours trying to solve this. =( Any help will be highly appreciated!

Answer 1

Here is a solution without recursion:
function convert($arr) {
$stack = array();
$output = array();
$arr[] = array('d' => -1); // Dummy record at the end
for($i = 0; $i < count($arr); $i++) {
while(!empty($stack) && $stack[count($stack) - 1]['d'] > $arr[$i]['d']) {
$current_d = $stack[count($stack) - 1]['d'];
$children = array();
while(!empty($stack) && $stack[count($stack) - 1]['d'] >= $current_d) {
$children[] = array_pop($stack);
}
$children = array_reverse($children);
if(empty($stack)) {
foreach($children as $child) {
$output[] = $child;
}
} else {
$stack[count($stack) - 1]['children'] = $children;
}
}
$stack[] = $arr[$i];
}
return $output;
}
$input = array (
array(
'n' => 'Articles',
'd' => 0
),
array(
'n' => 'Article 1',
'd' => 1
),
array(
'n' => 'Books',
'd' => 0
),
array(
'n' => 'Book 1',
'd' => 1
),
array(
'n' => 'Book 2',
'd' => 1
),
array(
'n' => 'Chapter 1',
'd' => 2
),
array(
'n' => 'Chapter 2',
'd' => 2
)
);
var_dump(convert($input));

Answer 2

Using the same $input:
$output = array();
function buildTree(&$input, &$output, &$current, $level = 0) {
if(!$input)
return;
$next = array_shift($input);
if($next['d'] == $level) {
$current[] = $next;
return buildTree($input, $output, $current, $level);
} else if($next['d'] == $level + 1) {
$current[count($current) - 1]['childrens'] = array($next);
return buildTree($input, $output, $current[count($current) - 1]['childrens'], $level + 1);
} else {
$output[] = $next;
return buildTree($input, $output, $output, 0);
}
}
buildTree($input, $output, $output);
var_dump($output);