fun solvePart1(pairs: Int = 40_000_000): Int =
        generator(startA, 16807)
            .zip(generator(startB, 48271))
            .take(pairs)
            .count { it.first == it.second }

    fun solvePart2(pairs: Int = 5_000_000): Int =
        generator(startA, 16807).filter { it % 4 == 0 }
            .zip(generator(startB, 48271).filter { it % 8 == 0 })
            .take(pairs)
            .count { it.first == it.second }


    private fun generator(start: Long, factor: Long): Sequence<Short> =
        generateSequence((start * factor) % 2147483647) { past ->
            (past * factor) % 2147483647
        }.map { it.toShort() }