General mess! Might pick at this over the next year.

2023/23/README.md

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+## \-\-\- 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?_

2023/23/code.go

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+package main
+
+import (
+	"github.com/jpillora/puzzler/harness/aoc"
+)
+
+func main() {
+	aoc.Harness(run)
+}
+
+// on code change, run will be executed 4 times:
+// 1. with: false (part1), and example input
+// 2. with: true (part2), and example input
+// 3. with: false (part1), and user input
+// 4. with: true (part2), and user input
+// the return value of each run is printed to stdout
+func run(part2 bool, input string) any {
+	// when you're ready to do part 2, remove this "not implemented" block
+	if part2 {
+		return "not implemented"
+	}
+	// solve part 1 here
+	return 42
+}

2023/23/input-example.txt

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