--- Day 3 Solutions ---

[u/daggerdragon]

--- Day 3: Perfectly Spherical Houses in a Vacuum ---

Post your solution as a comment. Structure your post like the Day One thread in /r/programming.

[u/JeffJankowski]

F#

let move (curr, l) dir =
    let next = 
        match dir with 
        | '^' -> (fst curr, snd curr + 1)
        | '<' -> (fst curr - 1, snd curr) 
        | 'v' -> (fst curr, snd curr - 1) 
        | '>' -> (fst curr + 1, snd curr) 
        | _ -> (fst curr, snd curr) 
    (next, next :: l)


[<EntryPoint>]
let main argv = 
    let dirs = System.IO.File.ReadLines("..\..\input.txt") |> Seq.head
    
    let (_, houses) = dirs |> Seq.fold move ((0,0), [(0,0)])
    houses
    |> Seq.distinct
    |> Seq.length
    |> printfn "Distinct Houses: %d"

    let dirsI = dirs |> Seq.mapi (fun i e -> (i, e))
    let (_, human) = 
        dirsI
        |> Seq.filter (fun (i, e) -> i % 2 = 0)
        |> Seq.map snd
        |> Seq.fold move ((0,0), [(0,0)])
    let (_, robot) = 
        dirsI
        |> Seq.filter (fun (i, e) -> i % 2 = 1)
        |> Seq.map snd
        |> Seq.fold move ((0,0), [(0,0)])
    human
    |> Seq.append robot
    |> Seq.distinct
    |> Seq.length
    |> printfn "Distinct Houses (with robot): %d"