This problem asks:

Given: A positive integer n (3≤n≤10000).

Return: The number of internal nodes of any unrooted binary tree having n leaves.

Required reading

  1. Binary tree
  2. Arborescence
  3. Rooted tree
  4. Unrooted binary tree

Restate the problem

Given the number of leaves in an unrooted binary tree, return the number of internal nodes.

Solution steps

In reading the Wikipedia page on unrooted binary trees, I read this snippet:

In an unrooted binary tree with n leaves, there will be n − 2 internal nodes…

Is it possible that the answer is simply n-2 for any given n?

I don’t even need to write any code to figure that out. I just download the dataset from Project Rosalind and return n-2 as the answer.

Yes! That works. Here’s a Project Rosalind first. I’ve solved a challenge with no code at all.