update one/fourteen.scm

1 files changed, 34 insertions, 20 deletions

diff --git a/one/fourteen.scm b/one/fourteen.scm
index 47156c7..4186238 100644
--- a/one/fourteen.scm
+++ b/one/fourteen.scm
@@ -2,28 +2,42 @@
 ;;;; International. See
 ;;;; <https://creativecommons.org/licenses/by-sa/4.0/>.
 
-;;; source from section 1.2.2
+;;; adapted from section 1.2.2
+;;; intolerable scheme drivel; ignore it.
 
 (define-module (one fourteen)
-  #:export (count-change
-            cc
-            first-denomination))
+  #:export (get-cc
+            cc-range
+            cc-diff-list))
 
-(define (count-change amount)
-  (cc amount 5))
+(define (get-cc)
+  (let ((no-of-steps 0))
+    (define (cc amount kinds-of-coins)
+      (set! no-of-steps (1+ no-of-steps))
+      (cond ((= amount 0) 1)
+            ((or (< amount 0) (= kinds-of-coins 0)) 0)
+            (else (+ (cc amount
+                         (- kinds-of-coins 1))
+                     (cc (- amount
+                            (first-denomination kinds-of-coins))
+                         kinds-of-coins)))))
+    (define (first-denomination kinds-of-coins)
+      (cond ((= kinds-of-coins 1) 1)
+            ((= kinds-of-coins 2) 5)
+            ((= kinds-of-coins 3) 10)
+            ((= kinds-of-coins 4) 25)
+            ((= kinds-of-coins 5) 50)))
+    (lambda (amount)
+      (cc amount 5)
+      no-of-steps)))
 
-(define (cc amount kinds-of-coins)
-  (cond ((= amount 0) 1)
-        ((or (< amount 0) (= kinds-of-coins 0)) 0)
-        (else (+ (cc amount
-                     (- kinds-of-coins 1))
-                 (cc (- amount
-                        (first-denomination kinds-of-coins))
-                     kinds-of-coins)))))
+(define (cc-range amount limit incr)
+  (cond ((> amount limit) '())
+        ((<= amount limit)
+         (cons ((get-cc) amount)
+              (cc-range (+ amount incr) limit incr)))))
 
-(define (first-denomination kinds-of-coins)
-  (cond ((= kinds-of-coins 1) 1)
-        ((= kinds-of-coins 2) 5)
-        ((= kinds-of-coins 3) 10)
-        ((= kinds-of-coins 4) 25)
-        ((= kinds-of-coins 5) 50)))
+(define (cc-diff-list l)
+  (cond ((= (length l) 1) '())
+        ((> (length l) 1) (cons (+ (* -1 (car l)) (cadr l))
+                                (cc-diff-list (cdr l))))))