Codingame: Snake AI, random safe moves

codingame-snake-ai.kt

import java.util.*
import java.lang.Integer.parseInt

typealias Coord = Pair<Int, Int>

fun Coord.x() = first
fun Coord.y() = second

typealias Move = Pair<Direction, Coord>

enum class Direction {
    N, S, W, E
}

fun coords(s: String) =
    s.split(",")
        .chunked(2)
        .map { (x, y) -> Coord(parseInt(x), parseInt(y)) }

fun moveCoord(coord: Coord, dir: Direction) =
    when (dir) {
        Direction.N -> Coord(coord.x(), coord.y() - 1)
        Direction.E -> Coord(coord.x() + 1, coord.y())
        Direction.S -> Coord(coord.x(), coord.y() + 1)
        else -> Coord(coord.x() - 1, coord.y())
    }

fun main(args: Array<String>) {
    val input = Scanner(System.`in`)
    val width = input.nextInt()
    val height = input.nextInt()
    val playercount = input.nextInt()
    val foodcount = input.nextInt()
    val myid = input.nextInt()

    // game loop

    while (true) {
        var others = mutableListOf<Coord>();
        var me = listOf<Coord>()

        fun debug(any: Any) = System.err.println(any)

        val aliveplayers = input.nextInt()
        for (i in 0 until aliveplayers) {
            val id = input.nextInt()
            val score = input.nextInt()
            val size = input.nextInt()
            val snake = input.next()

            if (id == myid) {
                me = coords(snake)
                debug(
                    """
                aliveplayers:
                id: $id
                score: $score
                size: $size
                snake: $snake
            """.trimIndent()
                )
            } else {
                others.addAll(coords(snake))
            }
        }

        val foods = mutableListOf<Coord>()
        for (i in 0 until foodcount) {
            val x = input.nextInt()
            val y = input.nextInt()
            foods.plus(Coord(x, y))
            //debug("food @ $x,$y")
        }

        fun isIllegalMove(c: Coord) =
            me.plus(others).contains(c)
                || c.x() >= width
                || c.y() >= height
                || c.x() < 0
                || c.y() < 0

        fun randMove(c: Coord) =
            Direction
                .values()
                .random()
                .let { Move(it, moveCoord(c, it)) }

        me.first()
            .let { pos -> generateSequence { randMove(pos) } }
            .dropWhile { move -> isIllegalMove(move.second) }
            .map { it.first }
            .first()
            .also(::println)
    }
}