Day21 Part1

Day21p1.kt

package day21

interface Dice {
    fun value(): Int
    fun values(count: Int): Sequence<Int>
    fun rollCount(): Int
}

class DeterministicDice(var value: Int = 1, val max: Int = 100): Dice {
    private var rollCount = 0
    override fun value(): Int {
        val r =  value
        value = (value % max) + 1
        rollCount  += 1
        return r
    }

    override fun values(count: Int): Sequence<Int> {
        return (0 until count).asSequence().map { value() }
    }

    override fun rollCount() = rollCount
}

class Position(var start: Int, val max: Int = 10) {
    var position = start - 1
    fun goBy(v: Int): Int {

        position  = (position + v) % max

        return position + 1
    }
}

class Player(private val position: Position) {
    var score = 0
    var moves = 0
    fun move(d: Dice) {
        val distance = d.values(3).sum()
        score += position.goBy(distance)
        moves += 1
    }
}


object Day21_Part1 {
    fun solve(start1: Int, start2: Int): Long {
        val stop = 1000
        val dice = DeterministicDice()
        val p1 = Player(Position(start1))
        val p2 = Player(Position(start2))
        while(p2.score < stop) {
            p1.move(dice)
            if(p1.score >= stop) {
                break
            }
            p2.move(dice)
        }
        return dice.rollCount().toLong()  * if(p1.score >= 1000)  + p2.score
        else p1.score
    }
}

fun main(args: Array<String>) {
    println(Day21_Part1.solve(3,7))
}