2017 Day 14 Complete!

2017/day14/problem

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+Advent of Code
+
+--- Day 14: Disk Defragmentation ---
+
+   Suddenly, a scheduled job activates the system's disk defragmenter. Were the situation different, you might sit and watch it for a while, but today, you just
+   don't have that kind of time. It's soaking up valuable system resources that are needed elsewhere, and so the only option is to help it finish its task as soon
+   as possible.
+
+   The disk in question consists of a 128x128 grid; each square of the grid is either free or used. On this disk, the state of the grid is tracked by the bits in a
+   sequence of knot hashes.
+
+   A total of 128 knot hashes are calculated, each corresponding to a single row in the grid; each hash contains 128 bits which correspond to individual grid
+   squares. Each bit of a hash indicates whether that square is free (0) or used (1).
+
+   The hash inputs are a key string (your puzzle input), a dash, and a number from 0 to 127 corresponding to the row. For example, if your key string were
+   flqrgnkx, then the first row would be given by the bits of the knot hash of flqrgnkx-0, the second row from the bits of the knot hash of flqrgnkx-1, and so on
+   until the last row, flqrgnkx-127.
+
+   The output of a knot hash is traditionally represented by 32 hexadecimal digits; each of these digits correspond to 4 bits, for a total of 4 * 32 = 128 bits. To
+   convert to bits, turn each hexadecimal digit to its equivalent binary value, high-bit first: 0 becomes 0000, 1 becomes 0001, e becomes 1110, f becomes 1111, and
+   so on; a hash that begins with a0c2017... in hexadecimal would begin with 10100000110000100000000101110000... in binary.
+
+   Continuing this process, the first 8 rows and columns for key flqrgnkx appear as follows, using # to denote used squares, and . to denote free ones:
+
+ ##.#.#..-->
+ .#.#.#.#
+ ....#.#.
+ #.#.##.#
+ .##.#...
+ ##..#..#
+ .#...#..
+ ##.#.##.-->
+ |      |
+ V      V
+
+   In this example, 8108 squares are used across the entire 128x128 grid.
+
+   Given your actual key string, how many squares are used?
+
+   Your puzzle answer was ________.
+
+--- Part Two ---
+
+   Now, all the defragmenter needs to know is the number of regions. A region is a group of used squares that are all adjacent, not including diagonals. Every used
+   square is in exactly one region: lone used squares form their own isolated regions, while several adjacent squares all count as a single region.
+
+   In the example above, the following nine regions are visible, each marked with a distinct digit:
+
+ 11.2.3..-->
+ .1.2.3.4
+ ....5.6.
+ 7.8.55.9
+ .88.5...
+ 88..5..8
+ .8...8..
+ 88.8.88.-->
+ |      |
+ V      V
+
+   Of particular interest is the region marked 8; while it does not appear contiguous in this small view, all of the squares marked 8 are connected when
+   considering the whole 128x128 grid. In total, in this example, 1242 regions are present.
+
+   How many regions are present given your key string?
+
+   Your puzzle answer was _____.
+
+   Both parts of this puzzle are complete! They provide two gold stars: **
+
+   At this point, you should return to your advent calendar and try another puzzle.
+
+   Your puzzle input was vbqugkhl.
+
+References
+
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+   . https://en.wikipedia.org/wiki/Defragmentation
+   . https://www.youtube.com/watch?v=kPv1gQ5Rs8A&t=37
+   . http://adventofcode.com/2017/day/10
+   . http://adventofcode.com/2017