<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/path-crossing/description/?envType=daily-question&amp;envId=2023-12-23">https://leetcode.com/problems/path-crossing/description/?envType=daily-question&amp;envId=2023-12-23</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/problems/1496/main.fsx">https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/problems/1496/main.fsx</a>
<pre><code class="lang-fsharp">let isPathCrossing (path: string) : bool =
 let rec isPathCrossing' cs x y visited =
 match cs with
 | [] -&gt; false
 | h :: t -&gt;
 let x', y' =
 match h with
 | 'N' -&gt; x, y + 1
 | 'E' -&gt; x + 1, y
 | 'S' -&gt; x, y - 1
 | 'W' -&gt; x - 1, y
 | _ -&gt; failwith "never reach here"

 if Set.contains (x', y') visited then
 true
 else
 isPathCrossing' t x' y' (Set.add (x', y') visited)

 isPathCrossing' (Seq.toList path) 0 0 (Set.empty |&gt; Set.add (0, 0))
</code></pre>

## URL

[https://leetcode.com/problems/path-crossing/description/?envType=daily-question&envId=2023-12-23](https://leetcode.com/problems/path-crossing/description/?envType=daily-question&envId=2023-12-23)

## Code

[https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/problems/1496/main.fsx](https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/problems/1496/main.fsx)

```fsharp
let isPathCrossing (path: string) : bool =
    let rec isPathCrossing' cs x y visited =
        match cs with
        | [] -> false
        | h :: t ->
            let x', y' =
                match h with
                | 'N' -> x, y + 1
                | 'E' -> x + 1, y
                | 'S' -> x, y - 1
                | 'W' -> x - 1, y
                | _ -> failwith "never reach here"

            if Set.contains (x', y') visited then
                true
            else
                isPathCrossing' t x' y' (Set.add (x', y') visited)

    isPathCrossing' (Seq.toList path) 0 0 (Set.empty |> Set.add (0, 0))
```

LeetCode 1496. Path Crossing in F#

URL

Code