PHP Taskbook Level 8.10

Given a form with two inputs. Numbers are entered into the inputs. After submitting the form, check whether these numbers are friendly or not.

Given some array:

<?php
	$arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
?>

Given a variable:

<?php
	$n = 3;
?>

Turn this array into a two-dimensional one, with $n elements per subarray.

Given an array:

[
	[1, 2, 3, 4, 5],
	[1, 2, 3],
	[1, 2],
]

Add enough empty strings to each subarray so that the number of elements in each subarray is equal to the number of elements in the longest subarray.

Given a list of some data for certain dates, stored in the following structure:

<?php
	$data = [
		[
			'year' =>  2019,
			'month' => 11,
			'day' => 20,
			'data' => ['array with data']
		],
		[
			'year' =>  2019,
			'month' => 11,
			'day' => 21,
			'data' => ['array with data']
		],
		[
			'year' =>  2019,
			'month' => 12,
			'day' => 25,
			'data' => ['array with data']
		],
		[
			'year' =>  2019,
			'month' => 12,
			'day' => 26,
			'data' => ['array with data']
		],
		[
			'year' =>  2020,
			'month' => 10,
			'day' => 29,
			'data' => ['array with data']
		],
		[
			'year' =>  2020,
			'month' => 10,
			'day' => 30,
			'data' => ['array with data']
		],
		[
			'year' =>  2020,
			'month' => 11,
			'day' => 19,
			'data' => ['array with data']
		],
		[
			'year' =>  2020,
			'month' => 11,
			'day' => 20,
			'data' => ['array with data']
		],
	]
?>

Write code that will convert the data structure into a structure like this:

[
	year1: [
		month1: [
			Day 1: [data array],
			Day 2: [data array],
			Day 3: [data array],
		],
		month2: [
			Day 1: [data array],
			Day 2: [data array],
			Day 3: [data array],
		]
	]
	year2: [
		month1: [
			Day 1: [data array],
			Day 2: [data array],
			Day 3: [data array],
		],
		month2: [
			Day 1: [data array],
			Day 2: [data array],
			Day 3: [data array],
		]
	]
]