104 lines
3.8 KiB
Plaintext
104 lines
3.8 KiB
Plaintext
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# Advent of Code
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--- Day 5: Hydrothermal Venture ---
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You come across a field of hydrothermal vents on the ocean floor! These vents constantly produce large, opaque clouds, so it would be best to avoid them if possible.
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They tend to form in lines; the submarine helpfully produces a list of nearby lines of vents (your puzzle input) for you to review. For example:
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0,9 -> 5,9
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8,0 -> 0,8
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9,4 -> 3,4
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2,2 -> 2,1
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7,0 -> 7,4
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6,4 -> 2,0
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0,9 -> 2,9
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3,4 -> 1,4
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0,0 -> 8,8
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5,5 -> 8,2
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Each line of vents is given as a line segment in the format x1,y1 -> x2,y2 where x1,y1 are the coordinates of one end the line segment and x2,y2 are the coordinates of the other end. These line segments include the points at both
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ends. In other words:
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• An entry like 1,1 -> 1,3 covers points 1,1, 1,2, and 1,3.
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• An entry like 9,7 -> 7,7 covers points 9,7, 8,7, and 7,7.
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For now, only consider horizontal and vertical lines: lines where either x1 = x2 or y1 = y2.
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So, the horizontal and vertical lines from the above list would produce the following diagram:
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.......1..
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..1....1..
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..1....1..
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.......1..
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.112111211
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..........
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..........
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..........
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..........
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222111....
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In this diagram, the top left corner is 0,0 and the bottom right corner is 9,9. Each position is shown as the number of lines which cover that point or . if no line covers that point. The top-left pair of 1s, for example, comes
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from 2,2 -> 2,1; the very bottom row is formed by the overlapping lines 0,9 -> 5,9 and 0,9 -> 2,9.
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To avoid the most dangerous areas, you need to determine the number of points where at least two lines overlap. In the above example, this is anywhere in the diagram with a 2 or larger - a total of 5 points.
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Consider only horizontal and vertical lines. At how many points do at least two lines overlap?
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Your puzzle answer was 5632.
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--- Part Two ---
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Unfortunately, considering only horizontal and vertical lines doesn't give you the full picture; you need to also consider diagonal lines.
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Because of the limits of the hydrothermal vent mapping system, the lines in your list will only ever be horizontal, vertical, or a diagonal line at exactly 45 degrees. In other words:
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• An entry like 1,1 -> 3,3 covers points 1,1, 2,2, and 3,3.
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• An entry like 9,7 -> 7,9 covers points 9,7, 8,8, and 7,9.
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Considering all lines from the above example would now produce the following diagram:
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1.1....11.
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.111...2..
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..2.1.111.
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...1.2.2..
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.112313211
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...1.2....
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..1...1...
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.1.....1..
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1.......1.
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222111....
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You still need to determine the number of points where at least two lines overlap. In the above example, this is still anywhere in the diagram with a 2 or larger - now a total of 12 points.
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Consider all of the lines. At how many points do at least two lines overlap?
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Your puzzle answer was 22213.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, you should return to your Advent calendar and try another puzzle.
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If you still want to see it, you can get your puzzle input.
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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/2021/about
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. https://adventofcode.com/2021/events
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. https://adventofcode.com/2021/settings
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. https://adventofcode.com/2021/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2021/support
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. https://adventofcode.com/2021
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. https://adventofcode.com/2021
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. https://adventofcode.com/2021/support
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. https://adventofcode.com/2021/sponsors
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. https://adventofcode.com/2021/leaderboard
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. https://adventofcode.com/2021/stats
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. https://adventofcode.com/2021/sponsors
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. https://en.wikipedia.org/wiki/Hydrothermal_vent
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. https://adventofcode.com/2021
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. https://adventofcode.com/2021/day/5/input
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