How to iterate this array to match all possible connections - arrays

Question

As a person that couldn't grasp recursion, I'm getting an array that has unlimited depth on parent <> child id links. This is a category list from an ecommerce platform (Shopee). And I'm trying to build a relationship list between all the categories and subcategories from the array below.
How to get this
Women's Clothing -> Tshirt -> Trending
-> Promotion
Shoes -> Hiking Shoe -> Winter Shoe
From the array below
$category = Array(
[0] => Array
(
[category_id] => 16
[parent_id] => 0
[category_name] => Women's Clothing
[has_children] => 1
)
[1] => Array
(
[category_id] => 18
[parent_id] => 16
[category_name] => Tshirt
[has_children] => 1
)
[2] => Array
(
[category_id] => 901
[parent_id] => 18
[category_name] => Trending
[has_children] => 0
)
[3] => Array
(
[category_id] => 23
[parent_id] => 0
[category_name] => Shoes
[has_children] => 1
)
[4] => Array
(
[category_id] => 100
[parent_id] => 23
[category_name] => Hiking Shoe
[has_children] => 1
)
[5] => Array
(
[category_id] => 120
[parent_id] => 100
[category_name] => Winter Shoe
[has_children] => 0
)
[6] => Array
(
[category_id] => 1400
[parent_id] => 18
[category_name] => Promotion
[has_children] => 0
)
)

Answer 1

You could first group the items by their parent key, and then perform a depth-first traversal through the data:
function dfs(&$childrenfor, $id, $path) {
if (isset($childrenfor[$id])) {
foreach($childrenfor[$id] as $item) {
yield from dfs($childrenfor, $item["category_id"], [...$path, $item["category_name"]]);
}
} else {
yield $path;
}
}
// first group the items by parent key
foreach ($category as $item) {
$childrenfor[$item["parent_id"]][] = $item;
}
// ...then use depth-first traversal to collect the root-to-leaf paths in the tree
$result = [...dfs($childrenfor, 0, [])];
The $result would have the following for your example data:
[
["Women's Clothing", "Tshirt", "Trending"],
["Women's Clothing", "Tshirt", "Promotion"],
["Shoes", "Hiking Shoe", "Winter Shoe"]
]
I guess you can take it from there to generate a format that suits you.