<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/island-perimeter/description/?envType=daily-question&amp;envId=2024-04-18">Island Perimeter - LeetCode</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202404/island_perimeter/main.fsx">https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202404/island_perimeter/main.fsx</a>
<pre><code class="lang-fsharp">let islandPerimeter (grid: int[,]) : int =
 let mutable ret = 0
 let rows, cols = Array2D.length1 grid, Array2D.length2 grid

 for i in 0 .. (rows - 1) do
 for j in 0 .. (cols - 1) do
 if grid.[i, j] = 1 then
 ret &lt;- ret + 4

 if i &gt;= 1 &amp;&amp; grid.[i - 1, j] = 1 then
 ret &lt;- ret - 2

 if j &gt;= 1 &amp;&amp; grid.[i, j - 1] = 1 then
 ret &lt;- ret - 2

 ret
</code></pre>

## URL

[Island Perimeter - LeetCode](https://leetcode.com/problems/island-perimeter/description/?envType=daily-question&envId=2024-04-18)

## Code

[https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202404/island\_perimeter/main.fsx](https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202404/island_perimeter/main.fsx)

```fsharp
let islandPerimeter (grid: int[,]) : int =
 let mutable ret = 0
 let rows, cols = Array2D.length1 grid, Array2D.length2 grid

 for i in 0 .. (rows - 1) do
 for j in 0 .. (cols - 1) do
 if grid.[i, j] = 1 then
 ret <- ret + 4

 if i >= 1 && grid.[i - 1, j] = 1 then
 ret <- ret - 2

 if j >= 1 && grid.[i, j - 1] = 1 then
 ret <- ret - 2

 ret
```

LeetCode 463. Island Perimeter in F#

URL

Code