Rosalind - Counting Phylogenetic Ancestors

Nov 27, 2020 rosalind

Problem:

Please find the problem here. http://rosalind.info/problems/inod/

Solution:

We knew that a rooted binary tree with n leaves has \( n - 1 \) internal nodes. An unrooted binary tree is simply a rooted binary tree with an extra leaf attached to the root. Therefore, the number of leaves increased by \( 1 \) but the number of internal nodes left unchanged. So an unrooted binary tree with \( n + 1 \) leaves has \( n - 1 \) internal nodes. In other words, an unrooted binary tree with \( n \) leaves has \( n - 2 \) internal nodes.

Code: