Question

Must use the Scheme language to solve the problem. Thanks!

Write a function deep-mult which takes a list as a parameter and computes the product of all numbers which appear anywhere in the list or in sublists. We will follow the usual mathematical convention that a product of no numbers is 1 (the multiplicative identity). You may find it useful to know that Scheme has a function number? which returns #t if its argument is numeric atom and #f otherwise.

Examples:

  (deep-mult '(5 a b 8 2))
 80

  (deep-mult '((4 (6 1)) 2 3 (4)))
 576

  (deep-mult '(these (aren't 77) (all 32 (numbers 93 here))))
 229152

  (deep-mult '())
 1

  (deep-mult '(no numbers here))
 1

Answer 1

CODE:

(define (deep-mult ls)
(cond ((null? ls) 1) ;;if list is empty then 1, as it multiplicative identity
((number? (car ls)) (* (car ls) (deep-mult (cdr ls)))) ;;If 1st element is number them multiply it with rest
((list? (car ls)) (* (deep-mult (car ls)) (deep-mult (cdr ls))));;if 1st element is a sublist multiply each element of it with rest of the sublist and then rest of the list.

(else (deep-mult (cdr ls))))) ;;else recursively traverse rest of the list.

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Snapshots:

Code:

(I) Without comments

(ii) with comments

Output: