Fibonacci / Memoization / Solution

fibonacci.php

<?php

declare(strict_types=1);

namespace App;

use ArrayObject;
use Closure;
use Generator;

function memoize(Closure $closure, ?ArrayObject $cache = null): Closure
{
    $cache = $cache ?? new ArrayObject();

    return
        /**
         * @psalm-suppress MixedAssignment
         *
         * @param mixed ...$arguments
         *
         * @return mixed
         */
        static fn (...$arguments) => $cache[
                sha1(serialize(json_encode($arguments)))
                ] ??= ($closure)(...$arguments);
}

function bench(Closure $closure, ...$arguments): array
{
    $benchGenerator = static function (Closure $closure, ...$arguments): Generator
    {
        yield microtime(true);
        yield $closure(...$arguments);
        yield microtime(true);
    };

    $result = iterator_to_array($benchGenerator($closure, ...$arguments));

    return [
        $result[1],
        $result[2] - $result[0],
    ];
}

$fibonacci = static function (int $number) use (&$fibonacci): int {
    return (1 >= $number) ?
        $number:
        $fibonacci($number - 1) + $fibonacci($number - 2);
};

$sleep = static function (int $number): int
{
    sleep($number);

    return $number;
};

$fibonacci = memoize($fibonacci);
$sleep = memoize($sleep);

var_dump(sprintf('[return: %s] [duration: %s]', ...bench($fibonacci, 10)));
var_dump(sprintf('[return: %s] [duration: %s]', ...bench($fibonacci, 10)));

var_dump(sprintf('[return: %s] [duration: %s]', ...bench($sleep, 10)));
var_dump(sprintf('[return: %s] [duration: %s]', ...bench($sleep, 10)));