Let's call this the "black-height" bh of the tree. It follows that every
such path contains exactly bh black and between 0 and bh red nodes. (The
extreme cases are a path containing only black nodes, and a path colored
Let's call this the "black-height" bh of the tree. It follows that every
such path contains exactly bh black and between 0 and bh red nodes. (The
extreme cases are a path containing only black nodes, and a path colored