<h2 id="heading-url">URL</h2>
<p><a target="_blank" href="https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree/description/">Longest ZigZag Path in a Binary Tree - LeetCode</a></p>
<h2 id="heading-code">Code</h2>
<p><a target="_blank" href="https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1372/main.fsx">https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1372/main.fsx</a></p>
<pre><code class="lang-plaintext">open System

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

let longestZigZa (root: Tree) : int =
    let rec longestZigZag' node depth goLeft =
        match node with
        | Leaf -&gt; depth - 1
        | Node(_, left, right) -&gt;
            if goLeft then
                Math.Max(longestZigZag' left (depth + 1) false, longestZigZag' right 1 true)
            else
                Math.Max(longestZigZag' right (depth + 1) true, longestZigZag' left 1 false)

    Math.Max(longestZigZag' root 0 true, longestZigZag' root 0 false)
</code></pre>


## URL

[Longest ZigZag Path in a Binary Tree - LeetCode](https://leetcode.com/problems/longest-zigzag-path-in-a-binary-tree/description/)

## Code

[https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1372/main.fsx](https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/problems/1372/main.fsx)

```plaintext
open System

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

let longestZigZa (root: Tree) : int =
    let rec longestZigZag' node depth goLeft =
        match node with
        | Leaf -> depth - 1
        | Node(_, left, right) ->
            if goLeft then
                Math.Max(longestZigZag' left (depth + 1) false, longestZigZag' right 1 true)
            else
                Math.Max(longestZigZag' right (depth + 1) true, longestZigZag' left 1 false)

    Math.Max(longestZigZag' root 0 true, longestZigZag' root 0 false)
```

LeetCode 1372. Longest ZigZag Path in a Binary Tree in F#

URL

Code