php递归 返回数组

<?php
function getChildren($array, $parentId = null) {
    $children = [];
    foreach ($array as $item) {
        if ($item['parent_id'] == $parentId) {
            $children[] = $item;
            $children = array_merge($children, getChildren($array, $item['id']));
        }
    }
    return $children;
}

// 示例数组
$data = [
    ['id' => 1, 'name' => 'A', 'parent_id' => null],
    ['id' => 2, 'name' => 'B', 'parent_id' => 1],
    ['id' => 3, 'name' => 'C', 'parent_id' => 1],
    ['id' => 4, 'name' => 'D', 'parent_id' => 2],
    ['id' => 5, 'name' => 'E', 'parent_id' => 2],
];

// 获取根节点的所有子节点
$children = getChildren($data);
print_r($children);
?>

ini_set('xdebug.max_nesting_level', 1000); // 增加Xdebug的嵌套级别限制

function getChildrenMemoized($array, $parentId = null, &$cache = []) {
    if (isset($cache[$parentId])) {
        return $cache[$parentId];
    }
    $children = [];
    foreach ($array as $item) {
        if ($item['parent_id'] == $parentId) {
            $children[] = $item;
            $children = array_merge($children, getChildrenMemoized($array, $item['id'], $cache));
        }
    }
    $cache[$parentId] = $children;
    return $children;
}

// 使用记忆化的递归函数
$childrenMemoized = getChildrenMemoized($data);
print_r($childrenMemoized);