Sum values from children to their parent in a variable dimension array - php

Question

I am trying to calculate and store the "Sum values from children to their parent in a variable dimension json/array".
We should start with the children with the lowest level, sum their values and store it in their parent. Move up one level, repeat the calculation, and so on.
Here is an example of given array (the "value" is "weight"):
[
"weight" => 0,
"children" => [
[
"weight" => 10
],
[
"weight" => 0,
"children" => [
[
"weight" => 60,
"children" => [
"weight" => 100
]
]
]
]
]
]
I would like to be able to dynamically calculate it like this :
[
"weight" => 110,
"children" => [
[
"weight" => 10
],
[
"weight" => 100,
"children" => [
[
"weight" => 100,
"children" => [
"weight" => 100
]
]
]
]
]
]
Do you have an idea ?
Thanks !!

Answer 1

If you want to update parent nodes with child nodes, then you must use a OOP concept. Because objects can store the pointer of parent node. Then you can easily update the parent node by using this pointer.
Define a two classes for Nodes and Node groups. Then you can implement your logics in these classes.
<?php
$arr = [
"weight" => 0,
"children" => [
[
"weight" => 10
],
[
"weight" => 0,
"children" => [
[
"weight" => 60,
"children" => [
"weight" => 100
]
]
]
]
]
];
interface CalculateWeight {
function calculateWeight();
}
class Node implements CalculateWeight {
public $weight = 0;
/** #var Group **/
public $parent = null;
public function __construct(?self $parent){
$this->parent = $parent;
}
function calculateWeight() {
if($this->parent){
$this->parent->plusWeight($this->weight);
}
}
public function setWeight(int $weight){
$this->weight = $weight;
}
// Creating nodes from an array
public static function fromArray(array $node, ?Node $parent=null): Node{
$weight = $node["weight"];
if(isset($node["children"])){
$group = new Group($parent);
// Checking the weather it has one child or multiple children
if(isset($node["children"][0])){
foreach($node["children"] as $node){
$group->addChild( Node::fromArray($node, $group));
}
} else {
$group->addChild(Node::fromArray($node["children"], $group));
}
return $group;
} else {
$node = new Node($parent);
$node->setWeight($weight);
return $node;
}
}
public function toArray(){
return ["weight"=> $this->weight];
}
}
class Group extends Node implements CalculateWeight {
public $childs = [];
/** #var Group **/
public $parent = null;
public function __construct(?self $parent){
$this->parent = $parent;
}
public function plusWeight(int $weight){
$this->weight += $weight;
}
public function addChild(Node $child){
$this->childs[] = $child;
}
public function calculateWeight(){
// Calculate children weights
foreach($this->childs as $child){
$child->calculateWeight();
}
// Updating calculated weight to parent node
if($this->parent){
$this->parent->plusWeight($this->weight);
}
}
public function toArray(){
return [
"weight"=> $this->weight,
"children"=> array_map(function($node){return $node->toArray();}, $this->childs)
];
}
}
$parentNode = Node::fromArray($arr,null);
$parentNode->calculateWeight();
var_dump($parentNode->toArray());