Data commit

Task/Roman-numerals-Decode/Racket/roman-numerals-decode.rkt

@@ -0,0 +1,17 @@
+#lang racket
+(define (decode/roman number)
+  (define letter-values
+    (map cons '(#\M #\D #\C #\L #\X #\V #\I) '(1000 500 100 50 10 5 1)))
+  (define (get-value letter)
+    (cdr (assq letter letter-values)))
+  (define lst (map get-value (string->list number)))
+  (+ (last lst)
+     (for/fold ((sum 0))
+       ((i (in-list lst)) (i+1 (in-list (cdr lst))))
+       (+ sum
+          (if (> i+1 i)
+              (- i)
+              i)))))
+
+(map decode/roman '("MCMXC" "MMVIII" "MDCLXVI"))
+;-> '(1990 2008 1666)