123 lines
5.2 KiB
Plaintext
123 lines
5.2 KiB
Plaintext
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Advent of Code
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--- Day 19: Tractor Beam ---
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Unsure of the state of Santa's ship, you borrowed the tractor beam technology from Triton. Time to test it out.
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When you're safely away from anything else, you activate the tractor beam, but nothing happens. It's hard to tell whether
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it's working if there's nothing to use it on. Fortunately, your ship's drone system can be configured to deploy a drone to
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specific coordinates and then check whether it's being pulled. There's even an Intcode program (your puzzle input) that gives
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you access to the drone system.
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The program uses two input instructions to request the X and Y position to which the drone should be deployed. Negative
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numbers are invalid and will confuse the drone; all numbers should be zero or positive.
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Then, the program will output whether the drone is stationary (0) or being pulled by something (1). For example, the
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coordinate X=0, Y=0 is directly in front of the tractor beam emitter, so the drone control program will always report 1 at
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that location.
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To better understand the tractor beam, it is important to get a good picture of the beam itself. For example, suppose you
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scan the 10x10 grid of points closest to the emitter:
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X
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0-> 9
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0#.........
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|.#........
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v..##......
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...###....
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....###...
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Y .....####.
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......####
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......####
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.......###
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9........##
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In this example, the number of points affected by the tractor beam in the 10x10 area closest to the emitter is 27.
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However, you'll need to scan a larger area to understand the shape of the beam. How many points are affected by the tractor
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beam in the 50x50 area closest to the emitter? (For each of X and Y, this will be 0 through 49.)
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Your puzzle answer was 217.
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--- Part Two ---
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You aren't sure how large Santa's ship is. You aren't even sure if you'll need to use this thing on Santa's ship, but it
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doesn't hurt to be prepared. You figure Santa's ship might fit in a 100x100 square.
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The beam gets wider as it travels away from the emitter; you'll need to be a minimum distance away to fit a square of that
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size into the beam fully. (Don't rotate the square; it should be aligned to the same axes as the drone grid.)
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For example, suppose you have the following tractor beam readings:
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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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.........#########......................
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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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.................########OOOOOOOOOO.....
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..................#######OOOOOOOOOO#....
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...................######OOOOOOOOOO###..
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....................#####OOOOOOOOOO#####
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.....................####OOOOOOOOOO#####
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.....................####OOOOOOOOOO#####
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......................###OOOOOOOOOO#####
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.......................##OOOOOOOOOO#####
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........................#OOOOOOOOOO#####
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.........................OOOOOOOOOO#####
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..........................##############
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..........................##############
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...........................#############
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............................############
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.............................###########
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In this example, the 10x10 square closest to the emitter that fits entirely within the tractor beam has been marked O. Within
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it, the point closest to the emitter (the only highlighted O) is at X=25, Y=20.
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Find the 100x100 square closest to the emitter that fits entirely within the tractor beam; within that square, find the point
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closest to the emitter. What value do you get if you take that point's X coordinate, multiply it by 10000, then add the
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point's Y coordinate? (In the example above, this would be 250020.)
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Your puzzle answer was 6840937.
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Both parts of this puzzle are complete! They provide two gold stars: **
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At this point, all that is left is for you to admire your Advent calendar.
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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/2019/about
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. https://adventofcode.com/2019/events
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. https://adventofcode.com/2019/settings
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. https://adventofcode.com/2019/auth/logout
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. Advent of Code Supporter
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https://adventofcode.com/2019/support
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. https://adventofcode.com/2019
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. https://adventofcode.com/2019
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. https://adventofcode.com/2019/support
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. https://adventofcode.com/2019/sponsors
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. https://adventofcode.com/2019/leaderboard
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. https://adventofcode.com/2019/stats
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. https://adventofcode.com/2019/sponsors
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. https://adventofcode.com/2019/day/9
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. https://adventofcode.com/2019
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. https://adventofcode.com/2019/day/19/input
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