AoC/2016/AoC2016.playground/Pages/Day 2.xcplaygroundpage/Contents.swift

let input = """
UULLULLUULLLURDLDUURRDRRLDURDULLRURDUDULLLUULURURLRDRRRRULDRUULLLLUUDURDULDRRDRUDLRRLDLUDLDDRURURUURRRDDDLLRUDURDULUULLRRULLRULDUDRDRLDLURURUDDUDLURUDUDURLURURRURLUDDRURRDLUURLLRURRDUDLULULUDULDLLRRRDLRDLDUDRDDDRRUURRRRRUURRDRRDLURDRRURDLLUULULLRURDLDDDRRLLRRUURULURUUDDLRRUDDRURUUDLRLRDLRURRRDULLDLRUDDUULRDULURUURDULUDLLRRLDDLRDLRUDRLDDRLRRRDURDULLRRRDRRLUURURDRRDRRLDLUDURURLDUURDRUDRDDRLDRRLDLURURULLUURUDUUDLRLL
LLLULLULDDULRLLURLLLRUUDDLRUULRLULLDLLRRDRLRLRLLDRUUURULDRDDLUDLLDUDULLLRLULLLRULDRDRUDLLRLRLLUDULRRRLDRUULDDULLDULULLUDUDLDRDURDLDLLDUDRRRDLUURRUURULLURLDURLRRLLDDUUULDRLUUDUDLURLULUDURRDRLLDDDDDRRULLRLDULULDDRUURRDLUDDDUDURDDRDRULULLLLUURDURUUUULUDLRURRULRDDRURURLLRLUUDUUURDLLDDLUDRLLLUDLLLLULRLURDRRRDUUDLLDLDDDURRDDRURUURDDRURRLDDDURDLLUURUUULRLUURRUDRLLDLURDUDRLULDLRLULULUDDLRDUDRUDLUULUULDURDRRRRLRULLUDRDDRDLDUDRDRRLDLLLLUDDLRULDLLDDUULDDRRULRRUURUDRDURLLLDDUUDRUUDLULLDR
UDUUULLDDDDLUDLDULRLRDLULLDDRULDURRLURRUDLRRUDURRDUDRRRUULRLLRLUDLDRRDUURDDRDRDUUUDUDLDLLRRLUURLUUUDDDUURLULURRLURRRDRDURURUDRLRUURUDRUDDDRDRDLDRDURDLDRRDUUDLLURLDDURRRLULDRDRLLRLLLRURLDURDRLDRUURRLDLDRLDDDRLDLRLDURURLLLLDDRDUDLRULULLRDDLLUDRDRRLUUULDRLDURURDUDURLLDRRDUULDUUDLLDDRUUULRRULDDUDRDRLRULUUDUURULLDLLURLRRLDDDLLDRRDDRLDDLURRUDURULUDLLLDUDDLDLDLRUDUDRDUDDLDDLDULURDDUDRRUUURLDUURULLRLULUURLLLLDUUDURUUDUULULDRULRLRDULDLLURDLRUUUDDURLLLLDUDRLUUDUDRRURURRDRDDRULDLRLURDLLRRDRUUUURLDRURDUUDLDURUDDLRDDDDURRLRLUDRRDDURDDRLDDLLRR
ULDRUDURUDULLUDUDURLDLLRRULRRULRUDLULLLDRULLDURUULDDURDUUDLRDRUDUDDLDRDLUULRRDLRUULULUUUDUUDDRDRLLULLRRDLRRLUDRLULLUUUUURRDURLLRURRULLLRLURRULRDUURRLDDRRDRLULDDRRDRLULLRDLRRURUDURULRLUDRUDLUDDDUDUDDUDLLRDLLDRURULUDRLRRULRDDDDDRLDLRRLUUDLUURRDURRDLDLDUDRLULLULRLDRDUDLRULLULLRLDDRURLLLRLDDDLLLRURDDDLLUDLDLRLUULLLRULDRRDUDLRRDDULRLLDUURLLLLLDRULDRLLLUURDURRULURLDDLRRUDULUURRLULRDRDDLULULRRURLDLRRRUDURURDURDULURULLRLDD
DURLRRRDRULDLULUDULUURURRLULUDLURURDDURULLRRUUDLRURLDLRUDULDLLRRULLLLRRLRUULDLDLLRDUDLLRLULRLLUUULULRDLDLRRURLUDDRRLUUDDRRUDDRRURLRRULLDDULLLURRULUDLRRRURRULRLLLRULLRRURDRLURULLDULRLLLULLRLRLLLDRRRRDDDDDDULUUDUDULRURDRUDRLUULURDURLURRDRRRRDRRLLLLUDLRRDURURLLULUDDLRLRLRRUURLLURLDUULLRRDURRULRULURLLLRLUURRULLLURDDDRURDUDDULLRULUUUDDRURUUDUURURRDRURDUDRLLRRULURUDLDURLDLRRRRLLUURRLULDDDUUUURUULDLDRLDUDULDRRULDRDULURRUURDU

"""
let inputTest = """
ULL
RRDDD
LURDL
UUUUD

"""

protocol KeyPad {
    associatedtype Digit

    var current: Digit { get }
    mutating func up()
    mutating func down()
    mutating func left()
    mutating func right()
}

func solve<T: KeyPad>(pad: T) -> [T.Digit] {
    var pad = pad
    var result: [T.Digit] = []
    for char in input {
        switch char {
        case "U": pad.up()
        case "D": pad.down()
        case "L": pad.left()
        case "R": pad.right()
        case "\n": result.append(pad.current)
        default: fatalError("Invalid input")
        }
    }
    return result
}

struct Part1Pad: KeyPad {
    var current: Int = 5

    mutating func up() {
        if current - 3 >= 1 {
            current -= 3
        }
    }

    mutating func down() {
        if current + 3 <= 9 {
            current += 3
        }
    }

    mutating func left() {
        if current != 1 && current != 4 && current != 7 {
            current -= 1
        }
    }

    mutating func right() {
        if current != 3 && current != 6 && current != 9 {
            current += 1
        }
    }
}

print("Part 1", solve(pad: Part1Pad()))

struct Part2Pad: KeyPad {
    let grid: [[Character]] = [
        Array("##1##"),
        Array("#234#"),
        Array("56789"),
        Array("#ABC#"),
        Array("##D##"),
    ]

    var x = 0
    var y = 2

    var current: Character {
        grid[y][x]
    }


    mutating func up() {
        if y > 0 && grid[y - 1][x] != "#" {
            y -= 1
        }
    }

    mutating func down() {
        if y < 4 && grid[y + 1][x] != "#" {
            y += 1
        }
    }

    mutating func left() {
        if x > 0 && grid[y][x - 1] != "#" {
            x -= 1
        }
    }

    mutating func right() {
        if x < 4 && grid[y][x + 1] != "#" {
            x += 1
        }
    }
}

print("Part 2:", solve(pad: Part2Pad()))