(define (xydy x y)
(not (> x y )))
(define (two-min x y)
(if (xydy x y) x y))
(define (three-min x y z)
(if (xydy (two-min x y) z) (two-min x y) z))
(define (two-max-sum x y z)
(- (+ x y z) (three-min x y z)))

觉得怪怪的，请大家指教，谢谢。

三數之和減三數最小就好了嘛
(define (max-two-sum a b c)
(- (+ a b c)
(min a b c)))

(define (max-two-sum a b c)
(- (+ a b c)
(min a b c)))

(define (max-two-sum a b c)
__(- (+ a b c)
____(min a b c)))
百度你犀利