Data commit

Task/Taxicab-numbers/Racket/taxicab-numbers.rkt

@@ -0,0 +1,27 @@
+#lang racket
+
+(define (cube x) (* x x x))
+
+;floor of cubic root
+(define (cubic-root x)
+  (let ([aprox (inexact->exact (round (expt x (/ 1 3))))])
+    (if (> (cube aprox) x)
+        (- aprox 1)
+        aprox)))
+
+(let loop ([p 1] [n 1])
+  (let ()
+    (define pairs
+      (for*/list ([j (in-range 1 (add1 (cubic-root (quotient n 2))))]
+                  [k (in-value (cubic-root (- n (cube j))))]
+                  #:when (= n (+ (cube j) (cube k))))
+        (cons j k)))
+    (if (>= (length pairs) 2)
+      (begin
+        (printf "~a: ~a" p n)
+        (for ([pair (in-list pairs)])
+          (printf " = ~a^3 + ~a^3" (car pair) (cdr pair)))
+          (newline)
+        (when (< p 25)
+          (loop (add1 p) (add1 n))))
+      (loop p (add1 n)))))