SICP 习题答案-Chapter1

; Exercise 1.3. Define a procedure that takes three numbers as arguments
; and returns the sum of the squares of the two larger numbers.

(define (square x) (* x x))
(define (sum-of-squares x y) (+ (square x) (square y)))
(define (sum-of-squares-largest-two x y z)
  (cond ((and (>= x y) (>= y z)) (sum-of-squares x y))
        ((and (>= x y) (>= z y)) (sum-of-squares x z))
        ((and (>= y x) (>= x z)) (sum-of-squares y x))
        ((and (>= y x) (>= z x)) (sum-of-squares y z))
        ((and (>= z x) (>= x y)) (sum-of-squares z x))
        ((and (>= z x) (>= y x)) (sum-of-squares z y))))

;; tests
(sum-of-squares-largest-two 1 2 3)
(sum-of-squares-largest-two 1 3 2)
(sum-of-squares-largest-two 2 3 1)
(sum-of-squares-largest-two 2 1 3)
(sum-of-squares-largest-two 3 1 2)
(sum-of-squares-largest-two 3 2 1)