fix

2016/day19/lang.rkt

@@ -9,7 +9,7 @@
 
 (define-macro (mb NUM-STR)
   #'(#%module-begin
-     (displayln (solve (string->number NUM-STR) #f))
+     #;(displayln (solve (string->number NUM-STR) #f))
      (displayln (solve (string->number NUM-STR) #t))))
 
 (define (idx-after vec x)
@@ -17,7 +17,7 @@
    (for/first ([idx (in-range (modulo (add1 x) (vector-length vec)) (vector-length vec))]
                #:when (vector-ref vec idx))
      idx)
-   (idx-after vec 0)))
+   (idx-after vec -1)))
 
 (define (solve num [circle? #f])
   (define elves (make-vector num #t))
@@ -26,7 +26,7 @@
       [(= elves-left 2) (add1 taker)]
       [else
        (define giver (for/fold ([elf taker])
-                               ([i (in-range (if circle? (floor (/ num 2)) 1))])
+                               ([i (in-range (if circle? (floor (/ elves-left 2)) 1))])
                        (idx-after elves elf)))
        (vector-set! elves giver #f)
        (loop (idx-after elves taker) (sub1 elves-left))])))