23.worksheet.sc

/*
--- Day 23: A Long Walk ---
The Elves resume water filtering operations! Clean water starts flowing over the
edge of Island Island.

They offer to help you go over the edge of Island Island, too! Just hold on
tight to one end of this impossibly long rope and they'll lower you down a safe
distance from the massive waterfall you just created.

As you finally reach Snow Island, you see that the water isn't really reaching
the ground: it's being absorbed by the air itself. It looks like you'll finally
have a little downtime while the moisture builds up to snow-producing levels.
Snow Island is pretty scenic, even without any snow; why not take a walk?

There's a map of nearby hiking trails (your puzzle input) that indicates paths
(.), forest (#), and steep slopes (^, >, v, and <).

For example:

#.#####################
#.......#########...###
#######.#########.#.###
###.....#.>.>.###.#.###
###v#####.#v#.###.#.###
###.>...#.#.#.....#...#
###v###.#.#.#########.#
###...#.#.#.......#...#
#####.#.#.#######.#.###
#.....#.#.#.......#...#
#.#####.#.#.#########v#
#.#...#...#...###...>.#
#.#.#v#######v###.###v#
#...#.>.#...>.>.#.###.#
#####v#.#.###v#.#.###.#
#.....#...#...#.#.#...#
#.#########.###.#.#.###
#...###...#...#...#.###
###.###.#.###v#####v###
#...#...#.#.>.>.#.>.###
#.###.###.#.###.#.#v###
#.....###...###...#...#
#####################.#

You're currently on the single path tile in the top row; your goal is to reach
the single path tile in the bottom row. Because of all the mist from the
waterfall, the slopes are probably quite icy; if you step onto a slope tile,
your next step must be downhill (in the direction the arrow is pointing). To
make sure you have the most scenic hike possible, never step onto the same tile
twice. What is the longest hike you can take?

In the example above, the longest hike you can take is marked with O, and your
starting position is marked S:

#S#####################
#OOOOOOO#########...###
#######O#########.#.###
###OOOOO#OOO>.###.#.###
###O#####O#O#.###.#.###
###OOOOO#O#O#.....#...#
###v###O#O#O#########.#
###...#O#O#OOOOOOO#...#
#####.#O#O#######O#.###
#.....#O#O#OOOOOOO#...#
#.#####O#O#O#########v#
#.#...#OOO#OOO###OOOOO#
#.#.#v#######O###O###O#
#...#.>.#...>OOO#O###O#
#####v#.#.###v#O#O###O#
#.....#...#...#O#O#OOO#
#.#########.###O#O#O###
#...###...#...#OOO#O###
###.###.#.###v#####O###
#...#...#.#.>.>.#.>O###
#.###.###.#.###.#.#O###
#.....###...###...#OOO#
#####################O#

This hike contains 94 steps. (The other possible hikes you could have taken were
90, 86, 82, 82, and 74 steps long.)

Find the longest hike you can take through the hiking trails listed on your map.
How many steps long is the longest hike?

--- Part Two ---
As you reach the trailhead, you realize that the ground isn't as slippery as you
expected; you'll have no problem climbing up the steep slopes.

Now, treat all slopes as if they were normal paths (.). You still want to make
sure you have the most scenic hike possible, so continue to ensure that you
never step onto the same tile twice. What is the longest hike you can take?

In the example above, this increases the longest hike to 154 steps:

#S#####################
#OOOOOOO#########OOO###
#######O#########O#O###
###OOOOO#.>OOO###O#O###
###O#####.#O#O###O#O###
###O>...#.#O#OOOOO#OOO#
###O###.#.#O#########O#
###OOO#.#.#OOOOOOO#OOO#
#####O#.#.#######O#O###
#OOOOO#.#.#OOOOOOO#OOO#
#O#####.#.#O#########O#
#O#OOO#...#OOO###...>O#
#O#O#O#######O###.###O#
#OOO#O>.#...>O>.#.###O#
#####O#.#.###O#.#.###O#
#OOOOO#...#OOO#.#.#OOO#
#O#########O###.#.#O###
#OOO###OOO#OOO#...#O###
###O###O#O###O#####O###
#OOO#OOO#O#OOO>.#.>O###
#O###O###O#O###.#.#O###
#OOOOO###OOO###...#OOO#
#####################O#

Find the longest hike you can take through the surprisingly dry hiking trails
listed on your map. How many steps long is the longest hike?
 */