AdventOfCode 2016 Day2

day2.fs

module Day2
open System

let code = @"
LRRLLLRDRURUDLRDDURULRULLDLRRLRLDULUDDDDLLRRLDUUDULDRURRLDULRRULDLRDUDLRLLLULDUURRRRURURULURRULRURDLULURDRDURDRLRRUUDRULLLLLDRULDDLLRDLURRLDUURDLRLUDLDUDLURLRLDRLUDUULRRRUUULLRDURUDRUDRDRLLDLDDDLDLRRULDUUDULRUDDRLLURDDRLDDUDLLLLULRDDUDDUUULRULUULRLLDULUDLLLLURRLDLUDLDDLDRLRRDRDUDDDLLLLLRRLLRLUDLULLDLDDRRUDDRLRDDURRDULLLURLRDLRRLRDLDURLDDULLLDRRURDULUDUDLLLDDDLLRLDDDLLRRLLURUULULDDDUDULUUURRUUDLDULULDRDDLURURDLDLULDUDUDDDDD
RUURUDRDUULRDDLRLLLULLDDUDRDURDLRUULLLLUDUDRRUDUULRRUUDDURDDDLLLLRRUURULULLUDDLRDUDULRURRDRDLDLDUULUULUDDLUDRLULRUDRDDDLRRUUDRRLULUULDULDDLRLURDRLURRRRULDDRLDLLLRULLDURRLUDULDRDUDRLRLULRURDDRLUDLRURDDRDULUDLDLLLDRLRUDLLLLLDUDRDUURUDDUDLDLDUDLLDLRRDLULLURLDDUDDRDUDLDDUULDRLURRDLDLLUUDLDLURRLDRDDLLDLRLULUDRDLLLDRLRLLLDRUULUDLLURDLLUURUDURDDRDRDDUDDRRLLUULRRDRULRURRULLDDDUDULDDRULRLDURLUDULDLDDDLRULLULULUDLDDRDLRDRDLDULRRLRLRLLLLLDDDRDDULRDULRRLDLUDDDDLUDRLLDLURDLRDLDRDRDURRDUDULLLDLUDLDRLRRDDDRRLRLLULDRLRLLLLDUUURDLLULLUDDRLULRDLDLDURRRUURDUDRDLLLLLLDDDURLDULDRLLDUDRULRRDLDUDRLLUUUDULURRUR
URRRLRLLDDDRRLDLDLUDRDRDLDUDDDLDRRDRLDULRRDRRDUDRRUUDUUUDLLUURLRDRRURRRRUDRLLLLRRDULRDDRUDLRLUDURRLRLDDRRLUULURLURURUDRULDUUDLULUURRRDDLRDLUDRDLDDDLRUDURRLLRDDRDRLRLLRLRUUDRRLDLUDRURUULDUURDRUULDLLDRDLRDUUDLRLRRLUDRRUULRDDRDLDDULRRRURLRDDRLLLRDRLURDLDRUULDRRRLURURUUUULULRURULRLDDDDLULRLRULDUDDULRUULRRRRRLRLRUDDURLDRRDDULLUULLDLUDDDUURLRRLDULUUDDULDDUULLLRUDLLLRDDDLUUURLDUDRLLLDRRLDDLUDLLDLRRRLDDRUULULUURDDLUR
UULDRLUULURDRLDULURLUDULDRRDULULUDLLDURRRURDRLRLLRLDDLURRDLUUDLULRDULDRDLULULULDDLURULLULUDDRRULULULRDULRUURRRUDLRLURDRURDRRUDLDDUURDUUDLULDUDDLUUURURLRRDLULURDURRRURURDUURDRRURRDDULRULRRDRRDRUUUUULRLUUUDUUULLRRDRDULRDDULDRRULRLDLLULUUULUUDRDUUUDLLULDDRRDULUURRDUULLUUDRLLDUDLLLURURLUDDLRURRDRLDDURLDLLUURLDUURULLLRURURLULLLUURUUULLDLRDLUDDRRDDUUDLRURDDDRURUURURRRDLUDRLUULDUDLRUUDRLDRRDLDLDLRUDDDDRRDLDDDLLDLULLRUDDUDDDLDDUURLDUDLRDRURULDULULUDRRDLLRURDULDDRRDLUURUUULULRURDUUDLULLURUDDRLDDUDURRDURRUURLDLLDDUUDLLUURDRULLRRUUURRLLDRRDLURRURDULDDDDRDD
LLRUDRUUDUDLRDRDRRLRDRRUDRDURURRLDDDDLRDURDLRRUDRLLRDDUULRULURRRLRULDUURLRURLRLDUDLLDULULDUUURLRURUDDDDRDDLLURDLDRRUDRLDULLRULULLRURRLLURDLLLRRRRDRULRUDUDUDULUURUUURDDLDRDRUUURLDRULDUDULRLRLULLDURRRRURRRDRULULUDLULDDRLRRULLDURUDDUULRUUURDRRLULRRDLDUDURUUUUUURRUUULURDUUDLLUURDLULUDDLUUULLDURLDRRDDLRRRDRLLDRRLUDRLLLDRUULDUDRDDRDRRRLUDUDRRRLDRLRURDLRULRDUUDRRLLRLUUUUURRURLURDRRUURDRRLULUDULRLLURDLLULDDDLRDULLLUDRLURDDLRURLLRDRDULULDDRDDLDDRUUURDUUUDURRLRDUDLRRLRRRDUULDRDUDRLDLRULDL
"
type Position = { x: int; y: int }

let keypad1 = Array2D.init 3 3 (fun x y -> (x * 3 + y + 1).ToString())

let clamp min max o n  =       
    if n < min then min
    elif n > max then max
    else n

let clamp1 o n  = clamp 0 2 o n

let keypad2 = array2D [|
               [|" "; " "; "1"; " "; " "|]
               [|" "; "2"; "3"; "4"; " "|]
               [|"5"; "6"; "7"; "8"; "9"|]
               [|" "; "A"; "B"; "C"; " "|]
               [|" "; " "; "D"; " "; " "|]
               |]

let extent o = abs (o - 2)
let clamp2 o n = clamp  (extent o) (4 - (extent o)) o n 

let keypadDecoder clamp (keypad: string [,]) = 
    let changeY n (l:Position) = {l with y = clamp l.x (l.y + n)  }
    let changeX n (l:Position) = {l with x = clamp l.y (l.x + n)  }

    let U (p:Position) = changeY -1 p
    let D (p:Position) = changeY 1 p
    let L (p:Position) = changeX -1 p
    let R (p:Position) = changeX 1 p
    let I (p:Position) = p

    let key p = keypad.[p.y,p.x]

    let interpretDirection letter = 
        match letter with
        | 'U' -> U
        | 'D' -> D
        | 'L' -> L
        | 'R' -> R
        | _ -> I

    let keyForLine startKey line = 
        let chars = List.ofSeq line
        let ops = List.map interpretDirection chars
        List.fold (fun position op -> op position) startKey ops
    
    let last l = List.rev l |> List.head

    let decode (s:string) (startKey:Position) : string = 
        let seperators = [|"\n";"\r"|]
        let lines = s.Split( seperators, StringSplitOptions.RemoveEmptyEntries )     
        let digits = Seq.fold (fun keys line -> keys @ [keyForLine (last keys) line ] )[startKey] lines
        let chars = Seq.map key digits.Tail  // the first key is the start key, which isn't part of the code, so just take the tail
        String.Concat( Array.ofSeq chars)
    
    decode

let day2 = 
    printfn "\n\nDay 2\n"    

    let startKey = {x=1; y=1}    
    let example1 = "ULL\nRRDDD\nLURDL\nUUUUD"    

    let decode1 = keypadDecoder clamp1 keypad1

    printfn "Example: %s" (decode1 example1 startKey)    
    printfn "Part 1: %s" (decode1 code startKey)
    
    let startKey = {x=0; y=2}    
    let decode2 = keypadDecoder clamp2 keypad2
    printfn "Example: %s" (decode2 example1 startKey)    
    printfn "Part 2: %s" (decode2 code startKey)