src/day01.lisp

   1 (asdf:load-system :adventofcode2020)
   2 (in-package #:adventofcode2020)
   3
   4 (defun calculate-expenses (&rest reports)
   5   (let ((prod (apply #'cartesian-product reports)))
   6     (loop for tuple in prod
   7           when (= (apply #'+ tuple) 2020)
   8           return (apply #'* tuple))))
   9
  10 (day 01 input
  11   (let ((report (int-list-from input)))
  12     (part1 (calculate-expenses report report))
  13     (part2 (calculate-expenses report report report))))
  14
  15 (def-suite day01)
  16 (in-suite day01)
  17
  18 (test simple-expenses
  19   (is (equal
  20         514579
  21         (let ((report '(1721 979 366 299 675 1456)))
  22           (calculate-expenses report report)))))
  23
  24 (test complex-expenses
  25   (is (equal
  26         241861950
  27         (let ((report '(1721 979 366 299 675 1456)))
  28           (calculate-expenses report report report)))))
  29
  30 (run! 'day01)