SICP Exercise 1.32-1.33

(define (accumulate combiner null-value term a next b)
  (if (> a b)
      null-value
      (combiner (term a )
        (accumulate combiner null-value term (next a) next b)
        )
      )
  )

(define (accumulate-iter combiner null-value term a next b)
  (define (iter null-value a b)
    (if (> a b)
        null-value
        (iter (combiner null-value (term a)) (next a) b)
        )
    )
  (iter null-value a b)
  )

(define (inc n) (+ n 1))  
   
(define (cube a) (* a a a))

(define (sum term a next b)  
  (accumulate + 0 term a next b)
  )
(define (sum-iter term a next b)  
  (accumulate-iter + 0 term a next b)
  )

(define (sum-cubes a b)    
  (sum cube a inc b)
  )  
(define (sum-cubes-iter a b)    
  (sum-iter cube a inc b)
  )  

(sum-cubes 1 10) 
(sum-cubes-iter 1 10) 
 
(define (filtered-accumulate combainer filter? null-value term a next b)
(if (> a b)
null-value
(if (filter? a)
(combainer (term a) (filtered-accumulate combainer filter? null-value term (next a) next b))
(filtered-accumulate combainer filter? null-value term (next a) next b)
)
)
)

(define (isok a) (= a a))

(define (sum-filtered-accumulate term a next b)
(filtered-accumulate + isok 0 term a next b)
)

(define (sum-filtered-accumulate-cubes a b)
(sum-filtered-accumulate cube a inc b)
)
(sum-filtered-accumulate-cubes 1 10)
 
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值