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<?php | |
$list = [ | |
[1, 2], | |
[2, 1], | |
[3, 1], | |
[4, 1], | |
[5, 2], | |
[6, 3], | |
[7, 3], | |
[8, 3], | |
[9, 4], | |
[10, 5], | |
[11, 5], | |
[12, 8], | |
[13, 8], | |
[14, 13], | |
[15, 14], | |
[16, 11], | |
[17, 16], | |
[18, 17], | |
]; | |
$children = []; | |
foreach ($list as [$child, $parent]) { | |
if (!isset($children[$child])) { | |
$children[$child] = null; | |
} | |
$children[$parent][] = $child; | |
} | |
$children = merge($children); | |
print_r($children); | |
function merge($arr) { | |
$xarr = $arr; | |
foreach ($arr as $parent => $item) { | |
if (!is_array($item)) continue; | |
foreach ($item as $child) { | |
if (isset($arr[$child])) { | |
$arr[$parent] = array_unique(array_merge($arr[$parent], $arr[$child])); | |
} | |
} | |
} | |
if ($xarr != $arr) { | |
return merge($arr); | |
} | |
return $xarr; | |
} |
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