Haskell中的最大树深度 [英] Maximum tree depth in Haskell

问题描述

我给了这个类型定义：

I am given this type definition:

data Tree = Leaf Char | Branch2 Char Tree Tree | Branch3 Char Tree Tree Tree

如何编写一个方法给我树的最大路径长度（计算路径中的节点数）？

How can I write a method that gives me the maximum path length of the tree (count the nodes in the path)?

推荐答案

你会想写一个递归函数来做到这一点。对于每个 Tree 构造函数，您需要在函数中使用不同的大小写。首先，你知道任何 Leaf 的深度都是 1 ，所以

You would want to write a recursive function to do this. For each Tree constructor, you'll need a different case in your function. To start with, you know that the depth of any Leaf is 1, so

maxDepth :: Tree -> Int
maxDepth (Leaf _) = 1
maxDepth (Branch2 c left right) = maximum [???]
maxDepth (Branch3 c left center right) = maximum [???]

我会让你完成剩下的功能。你也可以通过几种不同的方式来实现（比如使用 max 而不是最大）。

I'll let you finish the rest of the function. You could do it a few different ways as well (such as using max instead of maximum).

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