aoc2024-day1.scm

(use-modules (ice-9 textual-ports) (ice-9 pretty-print) (srfi srfi-1) (ice-9 receive) (srfi srfi-26))

(define (read-input)
  (let ([line (get-line (current-input-port))])
    (if (eof-object? line)
	'()
	(cons (filter identity (map string->number (string-split line #\space)))
	      (read-input)))))

(define (abs- a b) (abs (- a b)))

(receive (left right)
    (unzip2 (read-input))
  (pretty-print (fold + 0 (map abs- (sort left <) (sort right <))))
  (pretty-print (fold + 0 (map (λ (v) (* v (count (cut = v <>) right))) left))))