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#lang racket
(require "../../shared/lists.rkt")
(define (ordered-triples-sum n s)
(if (< n 3)
'()
(filter (lambda (triplet)
(= (fold-right + 0 triplet) s))
(flatmap (lambda (i)
(flatmap (lambda (pair)
(permutations (cons i pair)))
(unique-pairs (- i 1))))
(enumerate-interval 3 n)))))
((lambda ()
(newline)
(display (enumerate-interval 3 3))
(newline)
(display (ordered-triples-sum 4 8))))
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