#lang racket (require rackunit)
;; [List X Y Z] -> [List Z Y X]
;; switch items one and three in a 3-element list
(module+ test
(check-equal? (switch-one-and-three1 '(a b c)) '(c b a))
(check-equal? (switch-one-and-three1 '(1 2 3)) '(3 2 1)))
(define (switch-one-and-three1 ls)
(match ls
[`(,one ,two ,three) `(,three ,two ,one)]))
That's 50$ -- Matthias
On Sep 5, 2012, at 2:26 PM, Ashley Fowler wrote:
> Can anybody help me with this problem? I have an idea but would like some
> suggestions on how to start. The problem is below...
>
> Write a procedure (switch-one-and-three1 LS) that takes a list of
> exactly three items as its argument and returns the list with the first
> and third items switched around. You may assume the input list contains
> exactly three items
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