add a roundabout functional solution

1 files changed, 12 insertions, 10 deletions

diff --git a/aoc/day01/part1.neb b/aoc/day01/part1.neb
index 80a9fc8..76f949c 100644
--- a/aoc/day01/part1.neb
+++ b/aoc/day01/part1.neb
@@ -18,20 +18,22 @@
         (redef prev _item_))
     acc)
 
+; (a b c d e) => ((a b) (b c) (c d) (d e))
 (func pairwise (inp)
     (zip (list-reverse (rest (list-reverse inp))) (rest inp)))
 
-; what i really need to get working is 'apply
+(func abs (num)
+    (if (< num 0)
+        (* (- 0 1) num)
+        num))
+
 (func list-subtract (lst)
-    (- (first lst) (list-subtract (rest lst))))
+    (def ret (apply - lst))
+    (- (/ (abs ret) ret) 1))
 
+; this algorithm is very roundabout
 (func increase-count-iter-2 (inp)
-    ;(print (->string (list-reverse (rest (list-reverse inp)))))
-    ;(print (->string (rest inp)))
-    (def pairwise (zip (list-reverse (rest (list-reverse inp))) (rest inp)))
-    (print (->string pairwise))
-    )
-
+    (abs (/ (apply + (map list-subtract (pairwise inp))) 2)))
 
 (def lines 
     (map string->int
@@ -39,5 +41,5 @@
             (read-lines "input.txt"))))
 
 ;(print (->string (increase-count-recur lines 0)))
-;(print (->string (increase-count-iter lines 0)))
-(print (->string (increase-count-iter-2 lines 0)))
+(print (->string (increase-count-iter lines)))
+(print (->string (increase-count-iter-2 lines)))