function test($current, $n, $type = 1)
{
    $balls = [[65, 1], [75, 3], [85, 5], [0, 0]];

    list($prob, $cost) = $balls[$type];

    $price = 0;
    while ($current < $n) {
        if ($type == 3) {
            list($prob, $cost) = $current < 12 ? $balls[0] : $balls[2];
        }
        $success = rand(1, 100) <= $prob;
        if ($success) {
            $current++;
        } else {
            $current -= floor($current / 4);
        }
        $price += $cost;
    }
    return $price;
}

$h = fopen('out.csv', 'w');
$cnt = 1000000;

for ($from = 0; $from < 30; $from++) {

    $current = [];

    for ($type = 0; $type < 4; $type++) {

        if ($from > 15 && $type < 3) {
            continue;
        }

        $avg = 0;

        for ($i = 1; $i < $cnt; $i++) {
            $avg = $avg * ($i - 1) / $i + test($from, $from + 1, $type) / $i;
        }
        $current[$type] = $avg;

    }

    fputcsv($h, [
        'f' => $from + 1,
        'w' => $current[0] ?? 0,
        'b' => $current[1] ?? 0,
        'r' => $current[2] ?? 0,
        'o' => $current[3] ?? 0,
    ]);

    echo $from, PHP_EOL;

}