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hauleth.dev
1# Day 01
2
3```elixir
4Mix.install([:kino_aoc])
5```
6
7## Setup
8
9<!-- livebook:{"attrs":"eyJhc3NpZ25fdG8iOiJwdXp6bGVfaW5wdXQiLCJkYXkiOiIxIiwic2Vzc2lvbl9zZWNyZXQiOiJBRFZFTlRfT0ZfQ09ERV9TRVNTSU9OIiwieWVhciI6IjIwMjUifQ","chunks":null,"kind":"Elixir.KinoAOC.HelperCell","livebook_object":"smart_cell"} -->
10
11```elixir
12{:ok, puzzle_input} =
13 KinoAOC.download_puzzle("2025", "1", System.fetch_env!("LB_ADVENT_OF_CODE_SESSION"))
14```
15
16```elixir
17instructions =
18 puzzle_input
19 |> String.split("\n", trim: true)
20 |> Enum.map(fn <<dir>> <> rest ->
21 num = String.to_integer(rest)
22
23 if dir == ?R do
24 {div(num, 100), rem(num, 100)}
25 else
26 {div(num, 100), -rem(num, 100)}
27 end
28 end)
29```
30
31<!-- livebook:{"branch_parent_index":0} -->
32
33## Part 1
34
35```elixir
36Enum.scan(instructions, 50, fn {_rot, val}, curr ->
37 Integer.mod(curr + val, 100)
38end)
39|> Enum.count(& &1 == 0)
40```
41
42<!-- livebook:{"branch_parent_index":0} -->
43
44## Part 2
45
46```elixir
47<<0x434C49434B::40>>
48```
49
50```elixir
51Enum.reduce(instructions, {50, 0}, fn {rot, val}, {curr, sum} ->
52 next = curr + val
53
54 pass =
55 cond do
56 curr == 0 and next < 0 -> 0
57 next not in 0..99 -> 1
58 rem(next, 100) == 0 -> 1
59 true -> 0
60 end
61
62 {Integer.mod(next, 100), sum + pass + rot}
63end)
64|> elem(1)
65```
66
67<!-- livebook:{"offset":1270,"stamp":{"token":"XCP.fAfBqYepop325WQHLC6mJPz_Wpl7bDiz0qRbslvjG31mRJWcHALfstxgj_iOj3nf9_GCzh_WmPiNR4MnzZidF2bz_zMMXHTEo18hp1z3gQDdi5hTSO8UG4YSYnUEtGxO2g","version":2}} -->