<?php
header("Content-Type: text/plain; charset=utf-8");

class MoneyDivide
{
    /**
     * @var int
     */
    private $amount;

    /**
     * @param int $amount
     */
    public function __construct($amount)
    {
        $this->amount = $amount;
    }

    /**
     * @return array
     */
    public function getStepsTask1()
    {
        return $this->calculateTask1($this->amount);
    }

    /**
     * @return array
     */
    public function getStepsTask2()
    {
        return $this->calculateTask2($this->amount);
    }

    /**
     * @param int $amount
     * @return array [min,max]
     */
    private function calculateTask1($amount)
    {
        if ($amount < 4) {
            return [1,1];
        }
        $dividedAmount = floor($amount / 2);
        $remaining = $amount % 2;
        $stepsDivided = $this->calculateTask1($dividedAmount);
        $stepsDivided[1] += 1;
        $stepsDivided[0] = $stepsDivided[1];
        if ($remaining > 0) {
            $stepsDivided[0] = 1;
        }
        return $stepsDivided;
    }

    /**
     * @param int $amount
     * @return array [min,max]
     */
    private function calculateTask2($amount)
    {
        if ($amount < 4) {
            return [1,1];
        }
        $dividedAmount = floor($amount / 2);
        $remaining = $amount % 2;
        $stepsDivided = $this->calculateTask2($dividedAmount);
        $stepsDivided[1] += 1;
        $stepsDivided[0] = $stepsDivided[1];
        if ($remaining > 0) {
            $stepsDivided[0] = 1;
        }
        if ($amount == $this->amount) {
            $stepsDivided[1] += 1;
        }
        return $stepsDivided;
    }
}

$amount = 12;
$calculator = new MoneyDivide($amount);
$stepsTask1 = $calculator->getStepsTask1();
echo 'Задача 1 для ' .  $amount . ' монеток. Требуется взвешиваний: ';
if ($stepsTask1[0] == $stepsTask1[1]) {
    echo $stepsTask1[1];
} else {
    echo $stepsTask1[0] . '-' . $stepsTask1[1];
}

$stepsTask2 = $calculator->getStepsTask2();
echo "\nЗадача 2 для "   .  $amount . ' монеток. Требуется взвешиваний: ';
if ($stepsTask2[0] == $stepsTask2[1]) {
    echo $stepsTask2[1];
} else {
    echo $stepsTask2[0] . '-' . $stepsTask2[1];
}