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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,63 @@ | ||
| defmodule AdventOfCode.Y2023.Day15 do | ||
| @moduledoc """ | ||
| --- Day 15: Lens Library --- | ||
| Problem Link: https://adventofcode.com/2023/day/15 | ||
| Difficulty: s | ||
| Tags: hash ordered-map | ||
| """ | ||
| alias AdventOfCode.Helpers.InputReader | ||
| alias Aja.OrdMap | ||
|
|
||
| def input, do: InputReader.read_from_file(2023, 15) | ||
|
|
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| def run(input \\ input()) do | ||
| input = parse_1(input) | ||
| {run_1(input), run_2(input)} | ||
| end | ||
|
|
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| defp run_1(input), do: Enum.reduce(input, 0, &(&2 + hash(&1))) | ||
|
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| defp run_2(input) do | ||
| input | ||
| |> parse_2() | ||
| |> Enum.reduce(%{}, fn | ||
| {op, b, len}, acc -> | ||
| hash = hash(b) | ||
|
|
||
| case op do | ||
| :add -> Map.update(acc, hash, OrdMap.new(%{b => len}), &OrdMap.put(&1, b, len)) | ||
| :remove -> Map.update(acc, hash, OrdMap.new(%{}), &OrdMap.drop(&1, [b])) | ||
| end | ||
| end) | ||
| |> total_focus() | ||
| end | ||
|
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| defp total_focus(map) do | ||
| Enum.reduce(map, 0, fn {box, boxes}, acc -> | ||
| acc + | ||
| (boxes | ||
| |> OrdMap.to_list() | ||
| |> Enum.with_index(1) | ||
| |> Enum.reduce(0, &(&2 + row_focus(&1, box)))) | ||
| end) | ||
| end | ||
|
|
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| defp row_focus({{_, len}, slot}, box), do: (box + 1) * slot * len | ||
|
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| def parse_1(input \\ input()), do: String.split(input, ",", trim: true) | ||
|
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| def parse_2(commands) do | ||
| Enum.map(commands, fn cmd -> | ||
| case Regex.run(~r{([a-zA-Z]+)(=|-)([0-9]*)}, cmd) do | ||
| [_, label, "=", len] -> {:add, label, String.to_integer(len)} | ||
| [_, label, "-", ""] -> {:remove, label, 0} | ||
| end | ||
| end) | ||
| end | ||
|
|
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| def hash(lst) do | ||
| for ch <- String.to_charlist(lst), reduce: 0 do | ||
| acc -> rem((acc + ch) * 17, 256) | ||
| end | ||
| end | ||
| end |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,12 @@ | ||
| defmodule AdventOfCode.Y2023.Day15Test do | ||
| @moduledoc false | ||
|
|
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| use ExUnit.Case | ||
| @moduletag :y2315 | ||
|
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| alias AdventOfCode.Y2023.Day15, as: Solution | ||
|
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| test "Year 2023, Day 15 run/1" do | ||
| assert Solution.run() == {510_273, 212_449} | ||
| end | ||
| end |