171 lines
4.9 KiB
Plaintext
171 lines
4.9 KiB
Plaintext
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[1]Advent of Code
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• [2][About]
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• [3][Events]
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• [4][Shop]
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• [5][Settings]
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• [6][Log Out]
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br0xen [7](AoC++) 10*
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{ʼyearʼ:[8]2024}
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• [9][Calendar]
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• [10][AoC++]
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• [11][Sponsors]
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• [12][Leaderboard]
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• [13][Stats]
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Our [14]sponsors help make Advent of Code possible:
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[15]Jane Street - Weʼre a research-driven trading firm where curious
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people work together to solve the puzzle of global markets. Will our next
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great idea come from you? Our largest offices are in NYC, London, Hong
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Kong, and Singapore.
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--- Day 6: Guard Gallivant ---
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The Historians use their fancy [16]device again, this time to whisk you
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all away to the North Pole prototype suit manufacturing lab... in the year
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[17]1518! It turns out that having direct access to history is very
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convenient for a group of historians.
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You still have to be careful of time paradoxes, and so it will be
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important to avoid anyone from 1518 while The Historians search for the
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Chief. Unfortunately, a single guard is patrolling this part of the lab.
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Maybe you can work out where the guard will go ahead of time so that The
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Historians can search safely?
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You start by making a map (your puzzle input) of the situation. For
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example:
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....#.....
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.........#
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..........
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..#.......
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.......#..
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..........
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.#..^.....
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........#.
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#.........
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......#...
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The map shows the current position of the guard with ^ (to indicate the
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guard is currently facing up from the perspective of the map). Any
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obstructions - crates, desks, alchemical reactors, etc. - are shown as #.
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Lab guards in 1518 follow a very strict patrol protocol which involves
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repeatedly following these steps:
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• If there is something directly in front of you, turn right 90 degrees.
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• Otherwise, take a step forward.
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Following the above protocol, the guard moves up several times until she
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reaches an obstacle (in this case, a pile of failed suit prototypes):
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....#.....
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....^....#
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..........
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..#.......
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.......#..
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..........
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.#........
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........#.
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#.........
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......#...
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Because there is now an obstacle in front of the guard, she turns right
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before continuing straight in her new facing direction:
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....#.....
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........>#
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..........
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..#.......
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.......#..
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..........
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.#........
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........#.
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#.........
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......#...
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Reaching another obstacle (a spool of several very long polymers), she
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turns right again and continues downward:
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....#.....
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.........#
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..........
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..#.......
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.......#..
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..........
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.#......v.
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........#.
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#.........
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......#...
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This process continues for a while, but the guard eventually leaves the
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mapped area (after walking past a tank of universal solvent):
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....#.....
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.........#
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..........
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..#.......
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.......#..
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..........
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.#........
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........#.
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#.........
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......#v..
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By predicting the guard's route, you can determine which specific
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positions in the lab will be in the patrol path. Including the guard's
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starting position, the positions visited by the guard before leaving the
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area are marked with an X:
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....#.....
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....XXXXX#
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....X...X.
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..#.X...X.
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..XXXXX#X.
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..X.X.X.X.
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.#XXXXXXX.
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.XXXXXXX#.
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#XXXXXXX..
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......#X..
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In this example, the guard will visit 41 distinct positions on your map.
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Predict the path of the guard. How many distinct positions will the guard
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visit before leaving the mapped area?
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To begin, [18]get your puzzle input.
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Answer: [19]_____________________ [20][ [Submit] ]
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You can also [Shareon [21]Bluesky [22]Twitter [23]Mastodon] this puzzle.
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References
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Visible links
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1. https://adventofcode.com/
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2. https://adventofcode.com/2024/about
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3. https://adventofcode.com/2024/events
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4. https://cottonbureau.com/people/advent-of-code
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5. https://adventofcode.com/2024/settings
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6. https://adventofcode.com/2024/auth/logout
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7. Advent of Code Supporter
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https://adventofcode.com/2024/support
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8. https://adventofcode.com/2024
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9. https://adventofcode.com/2024
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10. https://adventofcode.com/2024/support
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11. https://adventofcode.com/2024/sponsors
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12. https://adventofcode.com/2024/leaderboard
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13. https://adventofcode.com/2024/stats
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14. https://adventofcode.com/2024/sponsors
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15. https://adventofcode.com/2024/sponsors/redirect?url=https%3A%2F%2Fwww%2Ejanestreet%2Ecom%2F
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16. https://adventofcode.com/2024/day/4
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17. https://adventofcode.com/2018/day/5
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18. https://adventofcode.com/2024/day/6/input
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21. https://bsky.app/intent/compose?text=%22Guard+Gallivant%22+%2D+Day+6+%2D+Advent+of+Code+2024+%23AdventOfCode+https%3A%2F%2Fadventofcode%2Ecom%2F2024%2Fday%2F6
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22. https://twitter.com/intent/tweet?text=%22Guard+Gallivant%22+%2D+Day+6+%2D+Advent+of+Code+2024&url=https%3A%2F%2Fadventofcode%2Ecom%2F2024%2Fday%2F6&related=ericwastl&hashtags=AdventOfCode
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23. javascript:void(0);
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