URL

Check If It Is a Straight Line - LeetCode

Code

https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1232/main.fsx

let checkStraightLine (coordinates: (int * int) list) : bool =
    let diff (x1, y1) (x2, y2) = x2 - x1, y2 - y1

    let x1, y1 = List.head coordinates
    let x2, y2 = List.item 1 coordinates
    let xDiff, yDiff = diff (x1, y1) (x2, y2)

    if xDiff = 0 then
        List.forall (fun (x, _) -> x = x1) coordinates
    else
        coordinates
        |> List.windowed 2
        |> List.forall (fun lst ->
            match lst with
            | (a1, b1) :: (a2, b2) :: [] -> a2 - a1 = xDiff && b2 - b1 = yDiff
            | _ -> failwith "never reach here")