483 lines
11 KiB
Markdown
483 lines
11 KiB
Markdown
## \-\-- Day 15: Warehouse Woes \-\--
|
|
|
|
You appear back inside your own mini submarine! Each Historian drives
|
|
their mini submarine in a different direction; maybe the Chief has his
|
|
own submarine down here somewhere as well?
|
|
|
|
You look up to see a vast school of [lanternfish](/2021/day/6) swimming
|
|
past you. On closer inspection, they seem quite anxious, so you drive
|
|
your mini submarine over to see if you can help.
|
|
|
|
Because lanternfish populations grow rapidly, they need a lot of food,
|
|
and that food needs to be stored somewhere. That\'s why these
|
|
lanternfish have built elaborate warehouse complexes operated by robots!
|
|
|
|
These lanternfish seem so anxious because they have lost control of the
|
|
robot that operates one of their most important warehouses! It is
|
|
currently running
|
|
amok,
|
|
pushing around boxes in the warehouse with no regard for lanternfish
|
|
logistics *or* lanternfish inventory management strategies.
|
|
|
|
Right now, none of the lanternfish are brave enough to swim up to an
|
|
unpredictable robot so they could shut it off. However, if you could
|
|
anticipate the robot\'s movements, maybe they could find a safe option.
|
|
|
|
The lanternfish already have a map of the warehouse and a list of
|
|
movements the robot will *attempt* to make (your puzzle input). The
|
|
problem is that the movements will sometimes fail as boxes are shifted
|
|
around, making the actual movements of the robot difficult to predict.
|
|
|
|
For example:
|
|
|
|
##########
|
|
#..O..O.O#
|
|
#......O.#
|
|
#.OO..O.O#
|
|
#..O@..O.#
|
|
#O#..O...#
|
|
#O..O..O.#
|
|
#.OO.O.OO#
|
|
#....O...#
|
|
##########
|
|
|
|
<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
|
|
vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
|
|
><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
|
|
<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
|
|
^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
|
|
^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
|
|
>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
|
|
<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
|
|
^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
|
|
v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^
|
|
|
|
As the robot (`@`) attempts to move, if there are any boxes (`O`) in the
|
|
way, the robot will also attempt to push those boxes. However, if this
|
|
action would cause the robot or a box to move into a wall (`#`), nothing
|
|
moves instead, including the robot. The initial positions of these are
|
|
shown on the map at the top of the document the lanternfish gave you.
|
|
|
|
The rest of the document describes the *moves* (`^` for up, `v` for
|
|
down, `<` for left, `>` for right) that the robot will attempt to make,
|
|
in order. (The moves form a single giant sequence; they are broken into
|
|
multiple lines just to make copy-pasting easier. Newlines within the
|
|
move sequence should be ignored.)
|
|
|
|
Here is a smaller example to get started:
|
|
|
|
########
|
|
#..O.O.#
|
|
##@.O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
<^^>>>vv<v>>v<<
|
|
|
|
Were the robot to attempt the given sequence of moves, it would push
|
|
around the boxes as follows:
|
|
|
|
Initial state:
|
|
########
|
|
#..O.O.#
|
|
##@.O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move <:
|
|
########
|
|
#..O.O.#
|
|
##@.O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move ^:
|
|
########
|
|
#.@O.O.#
|
|
##..O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move ^:
|
|
########
|
|
#.@O.O.#
|
|
##..O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move >:
|
|
########
|
|
#..@OO.#
|
|
##..O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move >:
|
|
########
|
|
#...@OO#
|
|
##..O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move >:
|
|
########
|
|
#...@OO#
|
|
##..O..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#......#
|
|
########
|
|
|
|
Move v:
|
|
########
|
|
#....OO#
|
|
##..@..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move v:
|
|
########
|
|
#....OO#
|
|
##..@..#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move <:
|
|
########
|
|
#....OO#
|
|
##.@...#
|
|
#...O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move v:
|
|
########
|
|
#....OO#
|
|
##.....#
|
|
#..@O..#
|
|
#.#.O..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move >:
|
|
########
|
|
#....OO#
|
|
##.....#
|
|
#...@O.#
|
|
#.#.O..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move >:
|
|
########
|
|
#....OO#
|
|
##.....#
|
|
#....@O#
|
|
#.#.O..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move v:
|
|
########
|
|
#....OO#
|
|
##.....#
|
|
#.....O#
|
|
#.#.O@.#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move <:
|
|
########
|
|
#....OO#
|
|
##.....#
|
|
#.....O#
|
|
#.#O@..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
Move <:
|
|
########
|
|
#....OO#
|
|
##.....#
|
|
#.....O#
|
|
#.#O@..#
|
|
#...O..#
|
|
#...O..#
|
|
########
|
|
|
|
The larger example has many more moves; after the robot has finished
|
|
those moves, the warehouse would look like this:
|
|
|
|
##########
|
|
#.O.O.OOO#
|
|
#........#
|
|
#OO......#
|
|
#OO@.....#
|
|
#O#.....O#
|
|
#O.....OO#
|
|
#O.....OO#
|
|
#OO....OO#
|
|
##########
|
|
|
|
The lanternfish use their own custom Goods Positioning System (GPS for
|
|
short) to track the locations of the boxes. The *GPS coordinate* of a
|
|
box is equal to 100 times its distance from the top edge of the map plus
|
|
its distance from the left edge of the map. (This process does not stop
|
|
at wall tiles; measure all the way to the edges of the map.)
|
|
|
|
So, the box shown below has a distance of `1` from the top edge of the
|
|
map and `4` from the left edge of the map, resulting in a GPS coordinate
|
|
of `100 * 1 + 4 = 104`.
|
|
|
|
#######
|
|
#...O..
|
|
#......
|
|
|
|
The lanternfish would like to know the *sum of all boxes\' GPS
|
|
coordinates* after the robot finishes moving. In the larger example, the
|
|
sum of all boxes\' GPS coordinates is `10092`. In the smaller example,
|
|
the sum is `2028`.
|
|
|
|
Predict the motion of the robot and boxes in the warehouse. After the
|
|
robot is finished moving, *what is the sum of all boxes\' GPS
|
|
coordinates?*
|
|
|
|
Your puzzle answer was `1568399`.
|
|
|
|
## \-\-- Part Two \-\-- {#part2}
|
|
|
|
The lanternfish use your information to find a safe moment to swim in
|
|
and turn off the malfunctioning robot! Just as they start preparing a
|
|
festival in your honor, reports start coming in that a *second*
|
|
warehouse\'s robot is *also* malfunctioning.
|
|
|
|
This warehouse\'s layout is surprisingly similar to the one you just
|
|
helped. There is one key difference: everything except the robot is
|
|
*twice as wide*! The robot\'s list of movements doesn\'t change.
|
|
|
|
To get the wider warehouse\'s map, start with your original map and, for
|
|
each tile, make the following changes:
|
|
|
|
- If the tile is `#`, the new map contains `##` instead.
|
|
- If the tile is `O`, the new map contains `[]` instead.
|
|
- If the tile is `.`, the new map contains `..` instead.
|
|
- If the tile is `@`, the new map contains `@.` instead.
|
|
|
|
This will produce a new warehouse map which is twice as wide and with
|
|
wide boxes that are represented by `[]`. (The robot does not change
|
|
size.)
|
|
|
|
The larger example from before would now look like this:
|
|
|
|
####################
|
|
##....[]....[]..[]##
|
|
##............[]..##
|
|
##..[][]....[]..[]##
|
|
##....[]@.....[]..##
|
|
##[]##....[]......##
|
|
##[]....[]....[]..##
|
|
##..[][]..[]..[][]##
|
|
##........[]......##
|
|
####################
|
|
|
|
Because boxes are now twice as wide but the robot is still the same size
|
|
and speed, boxes can be aligned such that they directly push two other
|
|
boxes at once. For example, consider this situation:
|
|
|
|
#######
|
|
#...#.#
|
|
#.....#
|
|
#..OO@#
|
|
#..O..#
|
|
#.....#
|
|
#######
|
|
|
|
<vv<<^^<<^^
|
|
|
|
After appropriately resizing this map, the robot would push around these
|
|
boxes as follows:
|
|
|
|
Initial state:
|
|
##############
|
|
##......##..##
|
|
##..........##
|
|
##....[][]@.##
|
|
##....[]....##
|
|
##..........##
|
|
##############
|
|
|
|
Move <:
|
|
##############
|
|
##......##..##
|
|
##..........##
|
|
##...[][]@..##
|
|
##....[]....##
|
|
##..........##
|
|
##############
|
|
|
|
Move v:
|
|
##############
|
|
##......##..##
|
|
##..........##
|
|
##...[][]...##
|
|
##....[].@..##
|
|
##..........##
|
|
##############
|
|
|
|
Move v:
|
|
##############
|
|
##......##..##
|
|
##..........##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##.......@..##
|
|
##############
|
|
|
|
Move <:
|
|
##############
|
|
##......##..##
|
|
##..........##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##......@...##
|
|
##############
|
|
|
|
Move <:
|
|
##############
|
|
##......##..##
|
|
##..........##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##.....@....##
|
|
##############
|
|
|
|
Move ^:
|
|
##############
|
|
##......##..##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##.....@....##
|
|
##..........##
|
|
##############
|
|
|
|
Move ^:
|
|
##############
|
|
##......##..##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##.....@....##
|
|
##..........##
|
|
##############
|
|
|
|
Move <:
|
|
##############
|
|
##......##..##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##....@.....##
|
|
##..........##
|
|
##############
|
|
|
|
Move <:
|
|
##############
|
|
##......##..##
|
|
##...[][]...##
|
|
##....[]....##
|
|
##...@......##
|
|
##..........##
|
|
##############
|
|
|
|
Move ^:
|
|
##############
|
|
##......##..##
|
|
##...[][]...##
|
|
##...@[]....##
|
|
##..........##
|
|
##..........##
|
|
##############
|
|
|
|
Move ^:
|
|
##############
|
|
##...[].##..##
|
|
##...@.[]...##
|
|
##....[]....##
|
|
##..........##
|
|
##..........##
|
|
##############
|
|
|
|
This warehouse also uses GPS to locate the boxes. For these larger
|
|
boxes, distances are measured from the edge of the map to the closest
|
|
edge of the box in question. So, the box shown below has a distance of
|
|
`1` from the top edge of the map and `5` from the left edge of the map,
|
|
resulting in a GPS coordinate of `100 * 1 + 5 = 105`.
|
|
|
|
##########
|
|
##...[]...
|
|
##........
|
|
|
|
In the scaled-up version of the larger example from above, after the
|
|
robot has finished all of its moves, the warehouse would look like this:
|
|
|
|
####################
|
|
##[].......[].[][]##
|
|
##[]...........[].##
|
|
##[]........[][][]##
|
|
##[]......[]....[]##
|
|
##..##......[]....##
|
|
##..[]............##
|
|
##..@......[].[][]##
|
|
##......[][]..[]..##
|
|
####################
|
|
|
|
The sum of these boxes\' GPS coordinates is `9021`.
|
|
|
|
Predict the motion of the robot and boxes in this new, scaled-up
|
|
warehouse. *What is the sum of all boxes\' final GPS coordinates?*
|
|
|
|
Your puzzle answer was `1575877`.
|
|
|
|
Both parts of this puzzle are complete! They provide two gold stars:
|
|
\*\*
|
|
|
|
At this point, you should [return to your Advent calendar](/2024) and
|
|
try another puzzle.
|
|
|
|
If you still want to see it, you can [get your puzzle
|
|
input](15/input).
|
|
|