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