** --- Day 24: Lobby Layout ---
Your raft makes it to the tropical island; it turns out that the small
crab was an excellent navigator. You make your way to the resort.

As you enter the lobby, you discover a small problem: the floor is being
renovated. You can't even reach the check-in desk until they've finished
installing the /new tile floor/.

The tiles are all /hexagonal/; they need to be arranged in a
[[https://en.wikipedia.org/wiki/Hexagonal_tiling][hex grid]] with a very
specific color pattern. Not in the mood to wait, you offer to help
figure out the pattern.

The tiles are all /white/ on one side and /black/ on the other. They
start with the white side facing up. The lobby is large enough to fit
whatever pattern might need to appear there.

A member of the renovation crew gives you a /list of the tiles that need
to be flipped over/ (your puzzle input). Each line in the list
identifies a single tile that needs to be flipped by giving a series of
steps starting from a /reference tile/ in the very center of the room.
(Every line starts from the same reference tile.)

Because the tiles are hexagonal, every tile has /six neighbors/: east,
southeast, southwest, west, northwest, and northeast. These directions
are given in your list, respectively, as =e=, =se=, =sw=, =w=, =nw=, and
=ne=. A tile is identified by a series of these directions with /no
delimiters/; for example, =esenee= identifies the tile you land on if
you start at the reference tile and then move one tile east, one tile
southeast, one tile northeast, and one tile east.

Each time a tile is identified, it flips from white to black or from
black to white. Tiles might be flipped more than once. For example, a
line like =esew= flips a tile immediately adjacent to the reference
tile, and a line like =nwwswee= flips the reference tile itself.

Here is a larger example:

#+BEGIN_EXAMPLE
  sesenwnenenewseeswwswswwnenewsewsw
  neeenesenwnwwswnenewnwwsewnenwseswesw
  seswneswswsenwwnwse
  nwnwneseeswswnenewneswwnewseswneseene
  swweswneswnenwsewnwneneseenw
  eesenwseswswnenwswnwnwsewwnwsene
  sewnenenenesenwsewnenwwwse
  wenwwweseeeweswwwnwwe
  wsweesenenewnwwnwsenewsenwwsesesenwne
  neeswseenwwswnwswswnw
  nenwswwsewswnenenewsenwsenwnesesenew
  enewnwewneswsewnwswenweswnenwsenwsw
  sweneswneswneneenwnewenewwneswswnese
  swwesenesewenwneswnwwneseswwne
  enesenwswwswneneswsenwnewswseenwsese
  wnwnesenesenenwwnenwsewesewsesesew
  nenewswnwewswnenesenwnesewesw
  eneswnwswnwsenenwnwnwwseeswneewsenese
  neswnwewnwnwseenwseesewsenwsweewe
  wseweeenwnesenwwwswnew
#+END_EXAMPLE

In the above example, 10 tiles are flipped once (to black), and 5 more
are flipped twice (to black, then back to white). After all of these
instructions have been followed, a total of /=10=/ tiles are /black/.

Go through the renovation crew's list and determine which tiles they
need to flip. After all of the instructions have been followed, /how
many tiles are left with the black side up?/

Your puzzle answer was =450=.

** --- Part Two ---
The tile floor in the lobby is meant to be a living art exhibit. Every
day, the tiles are all flipped according to the following rules:

- Any /black/ tile with /zero/ or /more than 2/ black tiles immediately
  adjacent to it is flipped to /white/.
- Any /white/ tile with /exactly 2/ black tiles immediately adjacent to
  it is flipped to /black/.

Here, /tiles immediately adjacent/ means the six tiles directly touching
the tile in question.

The rules are applied /simultaneously/ to every tile; put another way,
it is first determined which tiles need to be flipped, then they are all
flipped at the same time.

In the above example, the number of black tiles that are facing up after
the given number of days has passed is as follows:

#+BEGIN_EXAMPLE
  Day 1: 15
  Day 2: 12
  Day 3: 25
  Day 4: 14
  Day 5: 23
  Day 6: 28
  Day 7: 41
  Day 8: 37
  Day 9: 49
  Day 10: 37

  Day 20: 132
  Day 30: 259
  Day 40: 406
  Day 50: 566
  Day 60: 788
  Day 70: 1106
  Day 80: 1373
  Day 90: 1844
  Day 100: 2208
#+END_EXAMPLE

After executing this process a total of 100 times, there would be
/=2208=/ black tiles facing up.

/How many tiles will be black after 100 days?/

Your puzzle answer was =4059=.

Both parts of this puzzle are complete! They provide two gold stars: **

At this point, all that is left is for you to [[/2020][admire your
Advent calendar]].

If you still want to see it, you can [[file:24/input][get your puzzle
input]].

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