1 ;; The first three lines of this file were inserted by DrScheme. They record metadata
2 ;; about the language level of this file in a form that our tools can easily process.
3 #reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname |29|) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
4 Exercise 29.1.1.   A number tree is either a number or a pair of number trees. Develop the function sum-tree, which determines the sum of the numbers in a tree. How should we measure the size of a tree? What is its abstract running time?    Solution
5 
6 Exercise 29.1.2.   Hand-evaluate (maxi2 (list 0 1 2 3)) in a manner similar to our evaluation of (maxi (list 0 1 2 3)). What is the abstract running time of maxi2?    Solution
7 
8 A number tree is either
9 1. a number or
10 2. (make-tree nt1 nt2)
11 where nt1 and nt2 are number trees.
12 
13 (define-struct tree left right)