Happy numbers: Difference between revisions

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=={{header|Ol}}==

<syntaxhighlight lang="Scheme">

(define (number->list num)

(let loop ((num num) (lst #null))

(if (zero? num)

lst

(loop (quotient num 10) (cons (remainder num 10) lst)))))

(define (** x) (* x x))

(define (happy? num)

(let loop ((num num) (seen #null))

(cond

((= num 1) #true)

((memv num seen) #false)

(else

(loop (apply + (map ** (number->list num)))

(cons num seen))))))

(display "happy numbers: ")

(let loop ((n 1) (count 0))

(unless (= count 8)

(if (happy? n)

then

(display n) (display " ")

(loop (+ n 1) (+ count 1))

else

(loop (+ n 1) count))))

(print)

</syntaxhighlight>

<pre>

happy numbers: 1 7 10 13 19 23 28 31