Perform minor calculations on large integer lists.

index.php

<?php
/**
* A class for performing minor calculations on large integer lists.
*/
class Main
{
    private $buffSize;
    private $list;

    /**
     * Initiolize function.
     * @param  json $params
     * @return boolean
     */
    public function __construct($params)
    {
        echo "# Process started: " . date("m/d/Y h:i:s a", time()) . "\n";
        $result = json_decode($params);
        $this->buffSize = $result->buff_size;
        $this->list = explode(",", $this->clean($result->list));
        $this->calculate();

        echo "# Process finished: " . date("m/d/Y h:i:s a", time()) . "\n";

        return true;
    }

    /**
     * Calculations on large integer lists
     *
     * @return array
     */
    private function calculate()
    {
        $buffSize = $this->buffSize;
        $list = $this->list;

        $newArray = [];

        for ($i=0; $i < sizeof($list); $i++) {
            if ($i < $buffSize - 1)
            {
                $newArray[$i] = intval($list[$i]);
            } else
            {
                $checkedArray = array_slice($list, $i + 1 - $buffSize, $buffSize);

                $minMax = $this->minMax($checkedArray);
                $min = $minMax[0];
                $max = $minMax[1];
                $newArray[$i] = $min + $max;
            }
        }

        var_dump($newArray);

        return $newArray;
    }

    /**
     * Get min & max values from array.
     *
     * @param  array  $list
     * @return array
     */
    private function minMax(array $list) {
        if ($list == null || sizeof($list) < 1)
        {
            return;
        }

        $min = 0;
        $max = 0;

        // if only one element
        if (sizeof($list) == 1)
        {
            $max = $list[0];
            $min = $list[0];
        } else
        {
            if ($list[0] > $list[1])
            {
                $max = $list[0];
                $min = $list[1];
            } else
            {
                $max = $list[1];
                $min = $list[0];
            }

            for ($i = 2; $i <= sizeof($list) - 1; $i++)
            {
                if ($max < $list[$i])
                {
                    $max = $list[$i];
                } else if ($min > $list[$i])
                {
                    $min = $list[$i];
                }
            }
        }

        $returnArray[0] = $min;
        $returnArray[1] = $max;

        return $returnArray;
    }

    /**
     * Clean string from spaces and special characters.
     *
     * @param  $input
     * @return mixed
     */
    private function clean($input)
    {
        return preg_replace('/[^A-Za-z0-9,\-]/', '', str_replace(' ', '', trim($input)));
    }
}

$params = '{"buff_size": 3, "list": "[3, 5, 6, 4, 1, 5]"}';
$start = new Main($params);