<h2 id="heading-url">URL</h2>
<p><a target="_blank" href="https://leetcode.com/problems/check-if-it-is-a-straight-line/description/">Check If It Is a Straight Line - LeetCode</a></p>
<h2 id="heading-code">Code</h2>
<p><a target="_blank" href="https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1232/main.fsx">https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1232/main.fsx</a></p>
<pre><code class="lang-plaintext">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, _) -&gt; x = x1) coordinates
    else
        coordinates
        |&gt; List.windowed 2
        |&gt; List.forall (fun lst -&gt;
            match lst with
            | (a1, b1) :: (a2, b2) :: [] -&gt; a2 - a1 = xDiff &amp;&amp; b2 - b1 = yDiff
            | _ -&gt; failwith "never reach here")
</code></pre>


## URL

[Check If It Is a Straight Line - LeetCode](https://leetcode.com/problems/check-if-it-is-a-straight-line/description/)

## Code

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

```plaintext
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")
```

LeetCode 1232. Check If It Is a Straight Line in F#

URL

Code