X-Git-Url: https://git.sommitrealweird.co.uk/advent-of-code-2020.git/blobdiff_plain/a2ce7bb47964e226d4b10b791a038ca1f1fa67d7..fe0197cb1dc8f701b69ce52b9acb445351557c8d:/day3/summary.txt diff --git a/day3/summary.txt b/day3/summary.txt deleted file mode 100644 index 65228ae..0000000 --- a/day3/summary.txt +++ /dev/null @@ -1,77 +0,0 @@ ---- Day 3: Toboggan Trajectory --- -With the toboggan login problems resolved, you set off toward the airport. While travel by toboggan might be easy, it's certainly not safe: there's very minimal steering and the area is covered in trees. You'll need to see which angles will take you near the fewest trees. - -Due to the local geology, trees in this area only grow on exact integer coordinates in a grid. You make a map (your puzzle input) of the open squares (.) and trees (#) you can see. For example: - -..##....... -#...#...#.. -.#....#..#. -..#.#...#.# -.#...##..#. -..#.##..... -.#.#.#....# -.#........# -#.##...#... -#...##....# -.#..#...#.# -These aren't the only trees, though; due to something you read about once involving arboreal genetics and biome stability, the same pattern repeats to the right many times: - -..##.........##.........##.........##.........##.........##....... ---> -#...#...#..#...#...#..#...#...#..#...#...#..#...#...#..#...#...#.. -.#....#..#..#....#..#..#....#..#..#....#..#..#....#..#..#....#..#. -..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.# -.#...##..#..#...##..#..#...##..#..#...##..#..#...##..#..#...##..#. -..#.##.......#.##.......#.##.......#.##.......#.##.......#.##..... ---> -.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....# -.#........#.#........#.#........#.#........#.#........#.#........# -#.##...#...#.##...#...#.##...#...#.##...#...#.##...#...#.##...#... -#...##....##...##....##...##....##...##....##...##....##...##....# -.#..#...#.#.#..#...#.#.#..#...#.#.#..#...#.#.#..#...#.#.#..#...#.# ---> -You start on the open square (.) in the top-left corner and need to reach the bottom (below the bottom-most row on your map). - -The toboggan can only follow a few specific slopes (you opted for a cheaper model that prefers rational numbers); start by counting all the trees you would encounter for the slope right 3, down 1: - -From your starting position at the top-left, check the position that is right 3 and down 1. Then, check the position that is right 3 and down 1 from there, and so on until you go past the bottom of the map. - -The locations you'd check in the above example are marked here with O where there was an open square and X where there was a tree: - -..##.........##.........##.........##.........##.........##....... ---> -#..O#...#..#...#...#..#...#...#..#...#...#..#...#...#..#...#...#.. -.#....X..#..#....#..#..#....#..#..#....#..#..#....#..#..#....#..#. -..#.#...#O#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.#..#.#...#.# -.#...##..#..X...##..#..#...##..#..#...##..#..#...##..#..#...##..#. -..#.##.......#.X#.......#.##.......#.##.......#.##.......#.##..... ---> -.#.#.#....#.#.#.#.O..#.#.#.#....#.#.#.#....#.#.#.#....#.#.#.#....# -.#........#.#........X.#........#.#........#.#........#.#........# -#.##...#...#.##...#...#.X#...#...#.##...#...#.##...#...#.##...#... -#...##....##...##....##...#X....##...##....##...##....##...##....# -.#..#...#.#.#..#...#.#.#..#...X.#.#..#...#.#.#..#...#.#.#..#...#.# ---> -In this example, traversing the map using this slope would cause you to encounter 7 trees. - -Starting at the top-left corner of your map and following a slope of right 3 and down 1, how many trees would you encounter? - -Your puzzle answer was 234. - ---- Part Two --- -Time to check the rest of the slopes - you need to minimize the probability of a sudden arboreal stop, after all. - -Determine the number of trees you would encounter if, for each of the following slopes, you start at the top-left corner and traverse the map all the way to the bottom: - -Right 1, down 1. -Right 3, down 1. (This is the slope you already checked.) -Right 5, down 1. -Right 7, down 1. -Right 1, down 2. -In the above example, these slopes would find 2, 7, 3, 4, and 2 tree(s) respectively; multiplied together, these produce the answer 336. - -What do you get if you multiply together the number of trees encountered on each of the listed slopes? - -Your puzzle answer was 5813773056. - -Both parts of this puzzle are complete! They provide two gold stars: ** - -At this point, you should return to your Advent calendar and try another puzzle. - -If you still want to see it, you can get your puzzle input. - -You can also [Share] this puzzle.