2022-12-08 14:20:40 +00:00
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Advent of Code
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2022-12-08 14:19:41 +00:00
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2022-12-08 14:20:40 +00:00
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br0xen (AoC++) 16*
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2022-12-08 14:19:41 +00:00
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--- Day 8: Treetop Tree House ---
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The expedition comes across a peculiar patch of tall trees all planted carefully in a
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grid. The Elves explain that a previous expedition planted these trees as a reforestation
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effort. Now, they're curious if this would be a good location for a tree house.
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First, determine whether there is enough tree cover here to keep a tree house hidden. To
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do this, you need to count the number of trees that are visible from outside the grid
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when looking directly along a row or column.
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The Elves have already launched a quadcopter to generate a map with the height of each
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tree (your puzzle input). For example:
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30373
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25512
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65332
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33549
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35390
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Each tree is represented as a single digit whose value is its height, where 0 is the
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shortest and 9 is the tallest.
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A tree is visible if all of the other trees between it and an edge of the grid are
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shorter than it. Only consider trees in the same row or column; that is, only look up,
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down, left, or right from any given tree.
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All of the trees around the edge of the grid are visible - since they are already on the
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edge, there are no trees to block the view. In this example, that only leaves the
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interior nine trees to consider:
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• The top-left 5 is visible from the left and top. (It isn't visible from the right or
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bottom since other trees of height 5 are in the way.)
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• The top-middle 5 is visible from the top and right.
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• The top-right 1 is not visible from any direction; for it to be visible, there would
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need to only be trees of height 0 between it and an edge.
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• The left-middle 5 is visible, but only from the right.
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• The center 3 is not visible from any direction; for it to be visible, there would
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need to be only trees of at most height 2 between it and an edge.
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• The right-middle 3 is visible from the right.
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• In the bottom row, the middle 5 is visible, but the 3 and 4 are not.
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With 16 trees visible on the edge and another 5 visible in the interior, a total of 21
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trees are visible in this arrangement.
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Consider your map; how many trees are visible from outside the grid?
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Your puzzle answer was 1693.
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--- Part Two ---
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Content with the amount of tree cover available, the Elves just need to know the best
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spot to build their tree house: they would like to be able to see a lot of trees.
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To measure the viewing distance from a given tree, look up, down, left, and right from
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that tree; stop if you reach an edge or at the first tree that is the same height or
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taller than the tree under consideration. (If a tree is right on the edge, at least one
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of its viewing distances will be zero.)
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The Elves don't care about distant trees taller than those found by the rules above; the
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proposed tree house has large eaves to keep it dry, so they wouldn't be able to see
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higher than the tree house anyway.
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In the example above, consider the middle 5 in the second row:
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30373
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25512
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65332
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33549
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35390
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• Looking up, its view is not blocked; it can see 1 tree (of height 3).
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• Looking left, its view is blocked immediately; it can see only 1 tree (of height 5,
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right next to it).
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• Looking right, its view is not blocked; it can see 2 trees.
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• Looking down, its view is blocked eventually; it can see 2 trees (one of height 3,
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then the tree of height 5 that blocks its view).
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A tree's scenic score is found by multiplying together its viewing distance in each of
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the four directions. For this tree, this is 4 (found by multiplying 1 * 1 * 2 * 2).
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However, you can do even better: consider the tree of height 5 in the middle of the
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fourth row:
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30373
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25512
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65332
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33549
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35390
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• Looking up, its view is blocked at 2 trees (by another tree with a height of 5).
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• Looking left, its view is not blocked; it can see 2 trees.
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• Looking down, its view is also not blocked; it can see 1 tree.
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• Looking right, its view is blocked at 2 trees (by a massive tree of height 9).
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This tree's scenic score is 8 (2 * 2 * 1 * 2); this is the ideal spot for the tree house.
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Consider each tree on your map. What is the highest scenic score possible for any tree?
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Your puzzle answer was 422059.
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Both parts of this puzzle are complete! They provide two gold stars: **
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References
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Visible links
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. https://adventofcode.com/
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. https://adventofcode.com/2022/about
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. https://adventofcode.com/2022/events
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. https://adventofcode.com/2022/settings
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. https://adventofcode.com/2022/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2022/support
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022/support
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. https://adventofcode.com/2022/sponsors
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. https://adventofcode.com/2022/leaderboard
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. https://adventofcode.com/2022/stats
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. https://adventofcode.com/2022/sponsors
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. https://en.wikipedia.org/wiki/Tree_house
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. https://en.wikipedia.org/wiki/Quadcopter
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. https://en.wikipedia.org/wiki/Eaves
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. https://adventofcode.com/2022
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. https://adventofcode.com/2022/day/8/input
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