nodes(h) | = | leaves(h) + nodes(h-1) |
= | 2h + nodes(h-1) | |
= | 2h + 2h-1 + nodes(h-2) | |
= | 2h + 2h-1 + 2h-2 + ... + 4 + 2 + 1 |
Now rewrite nodes(h) as (2 x nodes(h)) - nodes(h):
2 x nodes(h) | = 2h+1 | + | 2h + 2h-1 + 2h-2 + ... + 4 + 2 |
− nodes(h) | = | − | 2h − 2h-1 − 2h-2 − ... − 4 − 2 − 1 |
| | | |
nodes(h) | = 2h+1 − 1 |
Exercise 8.10: Prove that nodes(h) = 2h+1 − 1 by induction on h.