My textbook says a "complete binary tree" is a "full binary tree" where every root is at the same level.
My conceptual understanding:
All this time, I was led by my textbook to believe a root is the "top-most vertex" in which all the other vertex are led away from it. So basically I am led to believe there can be only one root in a tree.
What does "where every root is at the same level" even mean?
Isn't a root suppose to be at level 0 all the time?