Game of Life

game.kt

package com.yoavst.testing

fun main(args: Array<String>) {
    /*
     * Read cells.
     * Format: y,x
     * Where y,x are zero based.
     * Stops when receive input "stop".
     */
    val input = generateSequence { readLine()?.takeIf { it != "stop" }?.split(',')?.let { (y, x) -> x.toInt() to y.toInt() } }
    // Generate matrix of dim*dim, given the input.
    var data = List(dim * dim) { Pair(it % dim, it / dim) in input }
    // storage for (max alive, turn for max).
    var results = data.size to 0
    // run for 50 generations.
    for (gen in 1..50) {
        /*
         * Generate next generation.
         * For each cell:
         * - Count how many neighbors it has. if between 3-5, stay alive, otherwise die.
         */
        data = data.mapIndexed { i, _ -> moves.count { (dx, dy) -> data[fixed(i.x() + dx) + fixed(i.y() + dy) * dim] } in 3..5 }
        data.size.let {
            if (it > results.first) results = it to gen
            println("gen $gen, alive: $it")
        }
    }
    println("best gen is ${results.second}")
}

const val dim = 10
// neighborhood
val moves = arrayOf(1 to 1, 1 to 0, 1 to -1, -1 to 0, -1 to 1, -1 to -1, 0 to 1, 0 to -1)
// fix bounds
inline fun fixed(num: Int) = if (num >= dim) 0 else if (num < 0) dim - 1 else num
inline fun Int.x() = this % dim
inline fun Int.y() = this / dim