From eb278c807fc7406f807fed395897388aa92403fb Mon Sep 17 00:00:00 2001
From: sloane <1699281+sloanelybutsurely@users.noreply.github.com>
Date: Fri, 8 Dec 2023 12:13:03 -0500
Subject: [PATCH] solve 2023 8.1
---
2023/README.md | 3 ++-
2023/lib/2023/8.ex | 51 ++++++++++++++++++++++++++++++++++++++++++++++
README.md | 2 +-
3 files changed, 54 insertions(+), 2 deletions(-)
create mode 100644 2023/lib/2023/8.ex
diff --git a/2023/README.md b/2023/README.md
index f919199..47ecd57 100644
--- a/2023/README.md
+++ b/2023/README.md
@@ -3,7 +3,7 @@
| S | M | T | W | T | F | S |
| :-: | :-: | :-: | :-: | :-: | :-: | :-: |
| | | | | | [1] | [2] |
-| [3] | [4] | [5] | 6 | [7] | 8 | 9 |
+| [3] | [4] | [5] | 6 | [7] | [8] | 9 |
| 10 | 11 | 12 | 13 | 14 | 15 | 16 |
| 17 | 18 | 19 | 20 | 21 | 22 | 23 |
| 24 | 25 | | | | | |
@@ -16,3 +16,4 @@
[5]: ./lib/2023/5.ex
<!-- [6]: ./lib/2023/6.ex -->
[7]: ./lib/2023/7.ex
+[8]: ./lib/2023/8.ex
diff --git a/2023/lib/2023/8.ex b/2023/lib/2023/8.ex
new file mode 100644
index 0000000..c6d37a1
--- /dev/null
+++ b/2023/lib/2023/8.ex
@@ -0,0 +1,51 @@
+import AOC
+import AOCHelpers
+
+aoc 2023, 8 do
+ def p1(input) do
+ {instructions, mappings} = read_input(input)
+
+ start = "AAA"
+ finish = "ZZZ"
+
+ all_but_last_step =
+ instructions
+ |> Stream.cycle()
+ |> Stream.scan(start, &step(&1, &2, mappings))
+ |> Stream.take_while(&(&1 != finish))
+ |> Enum.count()
+
+ all_but_last_step + 1
+ end
+
+ def p2(_input) do
+ end
+
+ def step("L", curr, mappings) do
+ mappings
+ |> Map.get(curr)
+ |> elem(0)
+ end
+
+ def step("R", curr, mappings) do
+ mappings
+ |> Map.get(curr)
+ |> elem(1)
+ end
+
+ def read_input(input) do
+ [instructions_string, _ | mapping_lines] = lines(input)
+ instructions = letters(instructions_string)
+
+ mappings =
+ mapping_lines
+ |> Enum.map(fn mapping_line ->
+ [_, key, left, right] = Regex.run(~r/^(.+) = \((.+), (.+)\)$/, mapping_line)
+
+ {key, {left, right}}
+ end)
+ |> Enum.into(%{})
+
+ {instructions, mappings}
+ end
+end
diff --git a/README.md b/README.md
index a4256b4..ed36e90 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@
1. [2020] **17/50** 🌟
1. [2021] **43/50** 🌟
1. [2022] **14/50** 🌟
-1. [2023] **11/50** 🌟
+1. [2023] **12/50** 🌟
[2015]: ./2015
[2017]: ./2017