Question

using Dr racket language

Write a function (add-mul L). The function consumes a (listof Int) It performs a series of mathematical operations. It starts with an answer of zero, then starting at the right, walks through the list L, and does the following operations: (1) If the next item in L is even, it adds the item to the answer so far. (2) If the next item on L is odd, it multiplies the answer by the item. For example, given (list 4 8 5 3 2) 2 is even, so add 0 and 2, giving 2; 3 is odd, so multiply 2 and 3, giving 6; 5 is odd, so multiply 6 and 5, giving 30 8 is even, so add 30 and 8, giving 38 4 is even, so add 38 and 4, giving 42 (add-mul (list 4 8 53 2)) #> 42 Exercise

Answer 1

Answer

#lang racket

(define (add-mul L) ;define the function add-mul with list argument L
(if (empty? L) 0 ;if L is empty return 0, else
(if (equal? (remainder (first L) 2) 0) ;if the first element of L is divisible by 0
(+ (first L) (add-mul (rest L))) ;add it with the return value of add-mul with rest of L as argument
(* (first L) (add-mul (rest L))) ;else multiply it with the return value of add-mul with rest of L as argument
)
)
)

Sample Output

Untitled DrRacket File Edit Vew Language Racket Insert Tabs Help #lang racket define the function add-mul with list argument L (define (add-mul L) (if (empty? L) 0 if L is empty return 0, else (if (equal? (remainder (first L) 2) 0) if the first element of L is divisible by 0 (first L) ( (first L) (add-mul (rest L))) add it with the return value of add-mul with rest of L as argument + (rest L)) ) (add-mul ;else multiply it with the return value of add-mul with rest of L as arqument Welcome to DrRacket, version 7.0 [3m]. Language: racket, with debugging; memory limit: 128 MB (add-mul (list 4 8 53 2)) 42 >