O'Halloran numbers: Difference between revisions

=={{header|Racket}}==

{{trans|Scala}}

<syntaxhighlight lang="Racket">

#lang racket

(define (main)

(let ([maximum-area 1000]

[ohalloran-numbers (make-hash)])

;; Initialize the hash table

(for ([i (in-range (quotient maximum-area 2))])

(hash-set! ohalloran-numbers i #t))

;; Calculate cuboid surface areas and update the hash table

(for* ([length (in-range 1 maximum-area)]

[width (in-range 1 (quotient maximum-area 2))]

[height (in-range 1 (quotient maximum-area 2))])

(let* ([half-area (+ (* length width) (* length height) (* width height))])

(when (< half-area (quotient maximum-area 2))

(hash-set! ohalloran-numbers half-area #f))))

;; Print the results

(printf "Values larger than 6 and less than 1,000 which cannot be the surface area of a cuboid:\n")

(for ([i (in-range 3 (quotient maximum-area 2))])

(when (hash-ref ohalloran-numbers i)

(printf "~a " (* i 2))))

(printf "\n")))

(main)

</syntaxhighlight>

{{out}}

<pre>

Values larger than 6 and less than 1,000 which cannot be the surface area of a cuboid:

8 12 20 36 44 60 84 116 140 156 204 260 380 420 660 924

</pre>