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Rare numbers: Difference between revisions
Add Racket solution
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imported>Sassela (Add Racket solution) |
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=={{header|Racket}}==
===naive===
<syntaxhighlight lang="racket" line>; 20231024 Racket programming naive solution
#lang racket
(require control)
(require text-block/text)
(define (is-palindrome n)
(define (digit-list n)
(if (zero? n)
'()
(cons (remainder n 10) (digit-list (quotient n 10)))))
(define (reverse-list lst)
(if (null? lst)
'()
(append (reverse-list (cdr lst)) (list (car lst)))))
(define digits (digit-list n))
(equal? digits (reverse-list digits)))
(define (perfect-square? n)
(if (rational? (sqrt n))
(= n (expt (floor (sqrt n)) 2))
false))
(define (reverse-number n)
(string->number (string-reverse (number->string n))))
(define (find-rare-numbers count)
(define rare-numbers '())
(define i 1)
(define (is-rare? n)
(and (not (is-palindrome n))
(let* ((r (reverse-number n))
(sum (+ n r))
(diff (- n r)))
(and (perfect-square? sum)
(perfect-square? diff)))))
(define start-time (current-inexact-milliseconds))
(while (< (length rare-numbers) count)
(cond [(is-rare? i)
(displayln (format "Number: ~a | Elapsed time: ~a ms" i (round (- (current-inexact-milliseconds) start-time))))
(set! rare-numbers (cons i rare-numbers))])
(set! i (+ i 1)))
(reverse rare-numbers))
(displayln "The first 5 rare numbers are:")
(for-each (λ (x) (display x) (display "\n")) (find-rare-numbers 5))
</syntaxhighlight>
=={{header|Raku}}==
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