Combine arrays based on array values PHP

Here sample arrays:

$array = ();
$array[] = array(
'filename' => 'File 1'
'folders' => array('Folder 1', 'Folder 2', 'Folder 3')
);

$array[] = array(
'filename' => 'File 2'
'folders' => array('Folder 1', 'Folder 2')
);

$array[] = array(
'filename' => 'File 3'
'folders' => array('Folder 1', 'Folder 2', 'Folder 3')
);

$array[] = array(
'filename' => 'File 4'
'folders' => array()
);

$array[] = array(
'filename' => 'File 5'
'folders' => array('Folder 1')
);

$array[] = array(
'filename' => 'File 6'
'folders' => array('Folder 1')
);

When we combine arrays, it should display array according to "folders". (Notice that, last array file is not in the folder ) So, desired output should be array version of this:

Root
- File 4
- Folder 1
-- File 5
-- File 6
-- Folder 2
--- File 2
--- Folder 3
---- File 1
---- File 3
.. etc..

Thank you.