89 lines
2.8 KiB
Plaintext
89 lines
2.8 KiB
Plaintext
Advent of Code
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--- Day 13: A Maze of Twisty Little Cubicles ---
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You arrive at the first floor of this new building to discover a much less
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welcoming environment than the shiny atrium of the last one. Instead, you
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are in a maze of twisty little cubicles, all alike.
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Every location in this area is addressed by a pair of non-negative integers
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(x,y). Each such coordinate is either a wall or an open space. You can't
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move diagonally. The cube maze starts at 0,0 and seems to extend infinitely
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toward positive x and y; negative values are invalid, as they represent a
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location outside the building. You are in a small waiting area at 1,1.
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While it seems chaotic, a nearby morale-boosting poster explains, the layout
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is actually quite logical. You can determine whether a given x,y coordinate
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will be a wall or an open space using a simple system:
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• Find x*x + 3*x + 2*x*y + y + y*y.
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• Add the office designer's favorite number (your puzzle input).
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• Find the binary representation of that sum; count the number of bits
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that are 1.
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• If the number of bits that are 1 is even, it's an open space.
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• If the number of bits that are 1 is odd, it's a wall.
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For example, if the office designer's favorite number were 10, drawing walls
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as # and open spaces as ., the corner of the building containing 0,0 would
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look like this:
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0123456789
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0 .#.####.##
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1 ..#..#...#
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2 #....##...
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3 ###.#.###.
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4 .##..#..#.
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5 ..##....#.
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6 #...##.###
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Now, suppose you wanted to reach 7,4. The shortest route you could take is
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marked as O:
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0123456789
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0 .#.####.##
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1 .O#..#...#
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2 #OOO.##...
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3 ###O#.###.
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4 .##OO#OO#.
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5 ..##OOO.#.
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6 #...##.###
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Thus, reaching 7,4 would take a minimum of 11 steps (starting from your
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current location, 1,1).
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What is the fewest number of steps required for you to reach 31,39?
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Your puzzle answer was 86.
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The first half of this puzzle is complete! It provides one gold star: *
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--- Part Two ---
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How many locations (distinct x,y coordinates, including your starting
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location) can you reach in at most 50 steps?
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Your puzzle input is still 1364.
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Answer: 127
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References
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Visible links
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. http://adventofcode.com/
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. http://adventofcode.com/2016/about
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. http://adventofcode.com/2016/support
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. http://adventofcode.com/2016/events
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. http://adventofcode.com/2016/settings
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. http://adventofcode.com/2016/auth/logout
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. http://adventofcode.com/2016
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. http://adventofcode.com/2016
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. http://adventofcode.com/2016/leaderboard
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. http://adventofcode.com/2016/stats
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. http://adventofcode.com/2016/sponsors
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. http://adventofcode.com/2016/sponsors
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. https://en.wikipedia.org/wiki/Binary_number
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. https://en.wikipedia.org/wiki/Bit
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