<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/largest-substring-between-two-equal-characters/description/?envType=daily-question&amp;envId=2023-12-31">https://leetcode.com/problems/largest-substring-between-two-equal-characters/description/?envType=daily-question&amp;envId=2023-12-31</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1624/main.fsx">https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1624/main.fsx</a>
<pre><code class="lang-fsharp">open System

let maxLengthBetweenCharacters (s: string) : int =
 let rec maxLengthBetweenCharacters' cs m acc =
 match cs with
 | [] -&gt; acc
 | (i, h) :: t -&gt;
 match Map.tryFind h m with
 | None -&gt; maxLengthBetweenCharacters' t (Map.add h i m) acc
 | Some(v) -&gt; maxLengthBetweenCharacters' t m (Math.Max(acc, i - v - 1))

 let cs = s |&gt; Seq.indexed |&gt; Seq.toList
 maxLengthBetweenCharacters' cs Map.empty -1
</code></pre>

## URL

[https://leetcode.com/problems/largest-substring-between-two-equal-characters/description/?envType=daily-question&envId=2023-12-31](https://leetcode.com/problems/largest-substring-between-two-equal-characters/description/?envType=daily-question&envId=2023-12-31)

## Code

[https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1624/main.fsx](https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1624/main.fsx)

```fsharp
open System

let maxLengthBetweenCharacters (s: string) : int =
    let rec maxLengthBetweenCharacters' cs m acc =
        match cs with
        | [] -> acc
        | (i, h) :: t ->
            match Map.tryFind h m with
            | None -> maxLengthBetweenCharacters' t (Map.add h i m) acc
            | Some(v) -> maxLengthBetweenCharacters' t m (Math.Max(acc, i - v - 1))

    let cs = s |> Seq.indexed |> Seq.toList
    maxLengthBetweenCharacters' cs Map.empty -1
```

LeetCode 1624. Largest Substring Between Two Equal Characters in F#

URL

Code