<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/sort-characters-by-frequency/description/">https://leetcode.com/problems/sort-characters-by-frequency/description/</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202402/sort_characters_by_frequency/main.fsx">https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202402/sort_characters_by_frequency/main.fsx</a>
<pre><code class="lang-fsharp">let frequencySort (s: string) : string =
 s
 |&gt; Seq.fold
 (fun acc c -&gt;
 match Map.tryFind c acc with
 | Some(v) -&gt; Map.add c (v + 1) acc
 | None -&gt; Map.add c 1 acc)
 Map.empty
 |&gt; Map.toList
 |&gt; List.sortWith (fun (c1, n1) (c2, n2) -&gt; if n1 = n2 then compare c1 c2 else compare n2 n1)
 |&gt; List.fold (fun acc (c, v) -&gt; seq { 1..v } |&gt; Seq.fold (fun acc _ -&gt; acc + string c) acc) ""
</code></pre>

## URL

[https://leetcode.com/problems/sort-characters-by-frequency/description/](https://leetcode.com/problems/sort-characters-by-frequency/description/)

## Code

[https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202402/sort\_characters\_by\_frequency/main.fsx](https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202402/sort_characters_by_frequency/main.fsx)

```fsharp
let frequencySort (s: string) : string =
    s
    |> Seq.fold
        (fun acc c ->
            match Map.tryFind c acc with
            | Some(v) -> Map.add c (v + 1) acc
            | None -> Map.add c 1 acc)
        Map.empty
    |> Map.toList
    |> List.sortWith (fun (c1, n1) (c2, n2) -> if n1 = n2 then compare c1 c2 else compare n2 n1)
    |> List.fold (fun acc (c, v) -> seq { 1..v } |> Seq.fold (fun acc _ -> acc + string c) acc) ""
```

LeetCode 451. Sort Characters By Frequency in F#

URL

Code