<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/adding-spaces-to-a-string/description/?envType=daily-question&amp;envId=2024-12-03">https://leetcode.com/problems/adding-spaces-to-a-string/description/?envType=daily-question&amp;envId=2024-12-03</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202412/adding_spaces_to_a_string/main.fsx">https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202412/adding_spaces_to_a_string/main.fsx</a>
<pre><code class="lang-fsharp">open System

let addSpaces (s: string) (spaces: int list) : string =
 let rec addSpaces' cs spaces (acc: char list) =
 match cs, spaces with
 | [], [] -&gt; acc |&gt; List.rev |&gt; String.Concat
 | [], _ -&gt; failwith "never reach here"
 | (_, h) :: t, [] -&gt; addSpaces' t [] (h :: acc)
 | (i, c) :: t1, j :: t2 -&gt;
 if i = j then
 addSpaces' t1 t2 (c :: ' ' :: acc)
 else
 addSpaces' t1 spaces (c :: acc)

 let cs = s |&gt; Seq.indexed |&gt; Seq.toList
 addSpaces' cs spaces []
</code></pre>

## URL

[https://leetcode.com/problems/adding-spaces-to-a-string/description/?envType=daily-question&envId=2024-12-03](https://leetcode.com/problems/adding-spaces-to-a-string/description/?envType=daily-question&envId=2024-12-03)

## Code

[https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202412/adding\_spaces\_to\_a\_string/main.fsx](https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202412/adding_spaces_to_a_string/main.fsx)

```fsharp
open System

let addSpaces (s: string) (spaces: int list) : string =
    let rec addSpaces' cs spaces (acc: char list) =
        match cs, spaces with
        | [], [] -> acc |> List.rev |> String.Concat
        | [], _ -> failwith "never reach here"
        | (_, h) :: t, [] -> addSpaces' t [] (h :: acc)
        | (i, c) :: t1, j :: t2 ->
            if i = j then
                addSpaces' t1 t2 (c :: ' ' :: acc)
            else
                addSpaces' t1 spaces (c :: acc)

    let cs = s |> Seq.indexed |> Seq.toList
    addSpaces' cs spaces []
```

LeetCode 2109. Adding Spaces to a String in F#

URL

Code