day2.kt

package com.advent

val data: List<String> = """DDDURLURURUDLDURRURULLRRDULRRLRLRURDLRRDUDRUDLRDUUDRRUDLLLURLUURLRURURLRLUDDURUULDURDRUUDLLDDDRLDUULLUDURRLUULUULDLDDULRLDLURURUULRURDULLLURLDRDULLULRRRLRLRULLULRULUUULRLLURURDLLRURRUUUDURRDLURUURDDLRRLUURLRRULURRDDRDULLLDRDDDDURURLLULDDULLRLDRLRRDLLURLRRUDDDRDLLRUDLLLLRLLRUDDLUUDRLRRRDRLRDLRRULRUUDUUDULLRLUDLLDDLLDLUDRURLULDLRDDLDRUDLDDLDDDRLLDUURRUUDLLULLRLDLUURRLLDRDLRRRRUUUURLUUUULRRUDDUDDRLDDURLRLRLLRRUDRDLRLDRRRRRRUDDURUUUUDDUDUDU
RLULUULRDDRLULRDDLRDUURLRUDDDUULUUUDDRDRRRLDUURDURDRLLLRDDRLURLDRRDLRLUURULUURDRRULRULDULDLRRDDRLDRUDUDDUDDRULURLULUDRDUDDDULRRRURLRRDLRDLDLLRLUULURLDRURRRLLURRRRRLLULRRRDDLRLDDUULDLLRDDRLLUUDRURLRULULRLRUULUUUUUDRURLURLDDUDDLRDDLDRRLDLURULUUDRDLULLURDLLLRRDRURUDDURRLURRDURURDLRUDRULUULLDRLRRDRLDDUDRDLLRURURLUDUURUULDURUDULRLRDLDURRLLDRDUDRUDDRLRURUDDLRRDLLLDULRRDRDRRRLURLDLURRDULDURUUUDURLDLRURRDRULLDDLLLRUULLLLURRRLLLDRRUDDDLURLRRRDRLRDLUUUDDRULLUULDURLDUUURUDRURUDRDLRRLDRURRLRDDLLLULUDDUULDURLRUDRDDD
RDDRUDLRLDDDRLRRLRRLUULDRLRUUURULRRLUURLLLRLULDDLDLRLULULUUDDDRLLLUDLLRUDURUDDLLDUDLURRULLRDLDURULRLDRLDLDRDDRUDRUULLLLRULULLLDDDULUUDUUDDLDRLRRDLRLURRLLDRLDLDLULRLRDLDLRLUULLDLULRRRDDRUULDUDLUUUUDUDRLUURDURRULLDRURUDURDUULRRULUULULRLDRLRLLRRRLULURLUDULLDRLDRDRULLUUUDLDUUUDLRDULRDDDDDDDDLLRDULLUDRDDRURUDDLURRUULUURURDUDLLRRRRDUDLURLLURURLRDLDUUDRURULRDURDLDRUDLRRLDLDULRRUDRDUUDRLURUURLDLUDLLRDDRDU
LLDDDDLUDLLDUDURRURLLLLRLRRLDULLURULDULDLDLLDRRDLUDRULLRUUURDRLLURDDLLUDDLRLLRDDLULRLDDRURLUDRDULLRUDDLUURULUUURURLRULRLDLDDLRDLDLLRUURDLUDRRRDDRDRLLUDDRLDRLLLRULRDLLRLRRDDLDRDDDUDUDLUULDLDUDDLRLDUULRULDLDULDDRRLUUURUUUDLRDRULDRRLLURRRDUDULDUDUDULLULLULULURLLRRLDULDULDLRDDRRLRDRLDRLUDLLLUULLRLLRLDRDDRUDDRLLDDLRULLLULRDDDLLLDRDLRULDDDLULURDULRLDRLULDDLRUDDUDLDDDUDRDRULULDDLDLRRDURLLRLLDDURRLRRULLURLRUDDLUURULULURLRUDLLLUDDURRLURLLRLLRRLDULRRUDURLLDDRLDLRRLULUULRRUURRRDULRLRLRDDRDULULUUDULLLLURULURRUDRLL
UULLULRUULUUUUDDRULLRLDDLRLDDLULURDDLULURDRULUURDLLUDDLDRLUDLLRUURRUDRLDRDDRRLLRULDLLRUUULLLDLDDULDRLRURLDRDUURLURDRUURUULURLRLRRURLDDDLLDDLDDDULRUDLURULLDDRLDLUDURLLLLLRULRRLLUDRUURLLURRLLRDRLLLRRDDDRRRDLRDRDUDDRLLRRDRLRLDDDLURUUUUULDULDRRRRLUDRLRDRUDUDDRULDULULDRUUDUULLUDULRLRRURDLDDUDDRDULLUURLDRDLDDUURULRDLUDDLDURUDRRRDUDRRDRLRLULDRDRLRLRRUDLLLDDDRURDRLRUDRRDDLDRRLRRDLUURLRDRRUDRRDLDDDLRDDLRDUUURRRUULLDDDLLRLDRRLLDDRLRRRLUDLRURULLDULLLUDLDLRLLDDRDRUDLRRDDLUU"""
        .split("\n")


fun main(args: Array<String>) {
    println(data.map { findKey(it) })
}

class Point(val x: Int, val y: Int)

val keypad = listOf(listOf(1, 2, 3),
                    listOf(4, 5, 6),
                    listOf(7, 8, 9))

fun findKey(line: String): Int {
    val result: Point = line.fold(Point(1, 1)) { acc: Point, char: Char ->
        val diff = charToDiff(char)
        (diff + acc).normalize()
    }
    return keypad[result.y][result.x]
}

fun Point.normalize(): Point {
    return Point(x.clamp(0, 2), y.clamp(0, 2))
}

fun Int.clamp(lo: Int, hi: Int) = Math.min(hi, (Math.max(lo, this)))

infix operator fun  Point.plus(acc: Point): Point {
    return Point(this.x + acc.x, this.y + acc.y)
}

fun  charToDiff(char: Char): Point =
    when (char) {
        'U' -> Point( 0, -1)
        'D' -> Point( 0,  1)
        'R' -> Point( 1,  0)
        'L' -> Point(-1,  0)
        else -> throw IllegalStateException()
    }