<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/description/?envType=daily-question&amp;envId=2024-10-09">Minimum Add to Make Parentheses Valid - LeetCode</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202410/minimum_add_to_make_parentheses_valid/main.fsx">https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202410/minimum_add_to_make_parentheses_valid/main.fsx</a>
<pre><code class="lang-fsharp">let minAddToMakeValid (s: string) : int =
 let rec minAddToMakeValid' cs opens unbalanced =
 match cs with
 | [] -&gt; opens + unbalanced
 | '(' :: t -&gt; minAddToMakeValid' t (opens + 1) unbalanced
 | _ :: t -&gt;
 if opens &gt; 0 then
 minAddToMakeValid' t (opens - 1) unbalanced
 else
 minAddToMakeValid' t opens (unbalanced + 1)

 minAddToMakeValid' (Seq.toList s) 0 0
</code></pre>

## URL

[Minimum Add to Make Parentheses Valid - LeetCode](https://leetcode.com/problems/minimum-add-to-make-parentheses-valid/description/?envType=daily-question&envId=2024-10-09)

## Code

[https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202410/minimum\_add\_to\_make\_parentheses\_valid/main.fsx](https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202410/minimum_add_to_make_parentheses_valid/main.fsx)

```fsharp
let minAddToMakeValid (s: string) : int =
    let rec minAddToMakeValid' cs opens unbalanced =
        match cs with
        | [] -> opens + unbalanced
        | '(' :: t -> minAddToMakeValid' t (opens + 1) unbalanced
        | _ :: t ->
            if opens > 0 then
                minAddToMakeValid' t (opens - 1) unbalanced
            else
                minAddToMakeValid' t opens (unbalanced + 1)

    minAddToMakeValid' (Seq.toList s) 0 0
```

LeetCode 921. Minimum Add to Make Parentheses Valid in F#

URL

Code