Main point: n is the number of external nodes
Option A:
Cant be the answer. Take an example binary tree with height 2, it will have min 3 nodes(left skew), n=1(leaf), sum of Iw = 2
Option C:
From above example, not true.
Option D:
If a tree has 2 nodes, n = 1 and Iw = 1. It holds true
Option B:
This always works….then why is it not the answer?
(B,D)