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;; https://adventofcode.com/2021/day/2
; optional -- 'sum' is more visually indicative than 'apply +'
(func sum (nums) (apply + nums))
(func do-the-thing (inp)
; order doesn't matter, so we can split horizontal and vertical
; movement without affecting the answer
(def vert-changes (filter (lambda (x) (in? (first x) (list "up" "down"))) inp))
(def horiz-changes (filter (lambda (x) (eq? (first x) "forward")) inp))
; turn "up"/"down" into +/- 1
(def vert-numbers
(map
(lambda (x)
(if (eq? (first x) "up")
(prepend (rest x) (- 1))
(prepend (rest x) 1)))
vert-changes))
(def vert
(sum ; add everything up
(map
(lambda (x) (* (first x) (last x))) ; multiply each pair together
vert-numbers)))
(def horiz
(sum
(map last horiz-changes))) ; we know there's only 2 elements in each list, and we want the last one
(print (concat "vert: " (->string vert)))
(print (concat "horiz: " (->string horiz)))
(* vert horiz))
(def lines
(map
(lambda (x) (list (first x) (string->int (first (rest x))))) ; convert second values to int
(map
(lambda (x) (split x " "))
(map strip
(read-lines "input.txt")))))
(print (->string lines))
(print (->string (do-the-thing lines)))
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