<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/number-of-laser-beams-in-a-bank/description/?envType=daily-question&amp;envId=2024-01-03">https://leetcode.com/problems/number-of-laser-beams-in-a-bank/description/?envType=daily-question&amp;envId=2024-01-03</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202401/number_of_laser_beams_in_a_bank/main.fsx">https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202401/number_of_laser_beams_in_a_bank/main.fsx</a>
<pre><code class="lang-fsharp">let numberOfBeams (bank: string list) : int =
 let rec numberOfBeams' bank prev acc =
 match bank with
 | [] -&gt; acc
 | h :: t -&gt;
 let ones = Seq.filter ((=) '1') h |&gt; Seq.length

 if ones &gt; 0 then
 numberOfBeams' t ones (acc + (prev * ones))
 else
 numberOfBeams' t prev acc

 numberOfBeams' bank 0 0
</code></pre>

## URL

[https://leetcode.com/problems/number-of-laser-beams-in-a-bank/description/?envType=daily-question&envId=2024-01-03](https://leetcode.com/problems/number-of-laser-beams-in-a-bank/description/?envType=daily-question&envId=2024-01-03)

## Code

[https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202401/number\_of\_laser\_beams\_in\_a\_bank/main.fsx](https://github.com/syohex/dotnet-study/blob/master/fsharp/leetcode/challenge/202401/number_of_laser_beams_in_a_bank/main.fsx)

```fsharp
let numberOfBeams (bank: string list) : int =
    let rec numberOfBeams' bank prev acc =
        match bank with
        | [] -> acc
        | h :: t ->
            let ones = Seq.filter ((=) '1') h |> Seq.length

            if ones > 0 then
                numberOfBeams' t ones (acc + (prev * ones))
            else
                numberOfBeams' t prev acc

    numberOfBeams' bank 0 0
```

LeetCode 2125. Number of Laser Beams in a Bank in F#

URL

Code