projects / adventofcode2020.git / blame
| Commit | Line | Data |
|---|---|---|
| 37dc4d4e JK |
1 | (in-package #:adventofcode2020) |
| 2 | ||
| 3 | (defun tree-collisions (slope tree-map) | |
| 4 | (destructuring-bind (rise run) slope | |
| 5 | (loop with terrain-width = (-> tree-map first length) | |
| 6 | for i upfrom 0 by run | |
| 7 | for j upfrom 0 | |
| 8 | for terrain-line in tree-map | |
| 9 | when (->> rise (mod j) (= 0)) | |
| 10 | counting (->> terrain-width | |
| 11 | (mod i) | |
| 12 | (char terrain-line) | |
| 13 | (char= #\#))))) | |
| 14 | ||
| 15 | (day 03 input | |
| 16 | (let ((tree-map (list-from input))) | |
| 17 | (part1 (tree-collisions '(1 3) tree-map)) | |
| 18 | (part2 (->> '((1 1) (1 3) (1 5) (1 7) (2 1)) | |
| 19 | (mapcar (fn* (tree-collisions _ tree-map))) | |
| 20 | (reduce #'*))))) | |
| 21 | ||
| 22 | (def-suite day03) | |
| 23 | (in-suite day03) | |
| 24 | ||
| 25 | (test single-collision-check | |
| 26 | (is (equal | |
| 27 | 7 | |
| 28 | (tree-collisions '(1 3) '("..##......." | |
| 29 | "#...#...#.." | |
| 30 | ".#....#..#." | |
| 31 | "..#.#...#.#" | |
| 32 | ".#...##..#." | |
| 33 | "..#.##....." | |
| 34 | ".#.#.#....#" | |
| 35 | ".#........#" | |
| 36 | "#.##...#..." | |
| 37 | "#...##....#" | |
| 38 | ".#..#...#.#"))))) | |
| 39 | ||
| 40 | ||
| 41 | (test multiple-collision-check | |
| 42 | (is (equal | |
| 43 | '(2 7 3 4 2) | |
| 44 | (mapcar (fn* (tree-collisions _ '("..##......." | |
| 45 | "#...#...#.." | |
| 46 | ".#....#..#." | |
| 47 | "..#.#...#.#" | |
| 48 | ".#...##..#." | |
| 49 | "..#.##....." | |
| 50 | ".#.#.#....#" | |
| 51 | ".#........#" | |
| 52 | "#.##...#..." | |
| 53 | "#...##....#" | |
| 54 | ".#..#...#.#"))) | |
| 55 | '((1 1) (1 3) (1 5) (1 7) (2 1)))))) | |
| 56 | ||
| 57 | (run! 'day03) |