请教一个简单的递归
$arr = array(
array(
'id' => 1,
'parentid' => 0,
'title' => 'a'
),
array(
'id' => 2,
'parentid' => 1,
'title' => 'a-1'
),
array(
'id' => 3,
'parentid' => 1,
'title' => 'a-1'
),
array(
'id' => 4,
'parentid' => 2,
'title' => 'a-1-1'
)
);
递归转换为数组如下:
$arr = array(
array(
'id' => 1,
'parentid' => 0,
'title' => 'a',
'child' => array(
array(
'id' => 2,
'parentid' => 1,
'title' => 'a-1',
'child' => array(
......
)
array(
'id' => 3,
'parentid' => 2,
'title' => 'a-2'
)
),
......
);
请问要如何写这个递归呢?
[解决办法]
function findChildren($list, $p=0){
$r = array();
foreach($list as $id=>$item){
if($item['parentid'] == $p) {
$r[$id] = $item;
if($t = findChildren($list, $item['id']) )
$r[$id]['children'][] = $t;
}
}
return $r;
}
$arr = array(
array(
'id' => 1,
'parentid' => 0,
'title' => 'a'
),
array(
'id' => 2,
'parentid' => 1,
'title' => 'a-1'
),
array(
'id' => 3,
'parentid' => 1,
'title' => 'a-1'
),
array(
'id' => 4,
'parentid' => 2,
'title' => 'a-1-1'
)
);
print_r(findChildren($arr));
Array
[parentid] => 1
[title] => a-1
[children] => Array
(
[0] => Array
(
[3] => Array
(
[id] => 4
[parentid] => 2
[title] => a-1-1
)
)
)
)
[2] => Array
(
[id] => 3
[parentid] => 1
[title] => a-1
)
)
)
)
)