<h2 id="heading-url">URL</h2>
<a target="_blank" href="https://leetcode.com/problems/diameter-of-binary-tree/description/?envType=daily-question&amp;envId=2024-02-27">https://leetcode.com/problems/diameter-of-binary-tree/description/?envType=daily-question&amp;envId=2024-02-27</a>
<h2 id="heading-code">Code</h2>
<a target="_blank" href="https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202402/diameter_of_binary_tree/main.fsx">https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202402/diameter_of_binary_tree/main.fsx</a>
<pre><code class="lang-fsharp">open System

type Tree =
 | Leaf
 | Node of int * Tree * Tree

let diameterOfBinaryTree (root: Tree) : int =
 let rec diameterOfBinaryTree' node =
 match node with
 | Leaf -&gt; 0, 0
 | Node(_, left, right) -&gt;
 let leftLen, leftMax = diameterOfBinaryTree' left
 let rightLen, rightMax = diameterOfBinaryTree' right

 let longest = Math.Max(leftLen + rightLen, Math.Max(leftMax, rightMax))
 1 + System.Math.Max(leftLen, rightLen), longest

 diameterOfBinaryTree' root |&gt; snd
</code></pre>

## URL

[https://leetcode.com/problems/diameter-of-binary-tree/description/?envType=daily-question&envId=2024-02-27](https://leetcode.com/problems/diameter-of-binary-tree/description/?envType=daily-question&envId=2024-02-27)

## Code

[https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202402/diameter\_of\_binary\_tree/main.fsx](https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202402/diameter_of_binary_tree/main.fsx)

```fsharp
open System

type Tree =
    | Leaf
    | Node of int * Tree * Tree

let diameterOfBinaryTree (root: Tree) : int =
    let rec diameterOfBinaryTree' node =
        match node with
        | Leaf -> 0, 0
        | Node(_, left, right) ->
            let leftLen, leftMax = diameterOfBinaryTree' left
            let rightLen, rightMax = diameterOfBinaryTree' right

            let longest = Math.Max(leftLen + rightLen, Math.Max(leftMax, rightMax))
            1 + System.Math.Max(leftLen, rightLen), longest

    diameterOfBinaryTree' root |> snd
```

LeetCode 543. Diameter of Binary Tree in F#

URL

Code