src/day01.lisp

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