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# Untitled notebook
## Section
```elixir
defmodule Advent1 do
def solve do
File.stream!("#{File.cwd!()}/input/14_example.txt")
|> Stream.map(&String.trim/1)
|> Stream.map(&String.split/1)
|> extract_koords_cave()
# |> IO.inspect(label: "cave coords")
end
# the cave is filled with paths of stones
def extract_koords_cave(paths) do
paths
|> Stream.map(&Advent1.extract_coords_path/1)
# |> IO.inspect(label: "path coords")
|> Enum.reduce(&MapSet.union/2)
end
# one line of input describes one path
def extract_coords_path(path) do
path
|> Stream.filter(fn x -> x != "->" end)
|> Stream.map(fn x -> String.split(x, ",") end)
|> Stream.map(fn [x, y] -> [String.to_integer(x), String.to_integer(y)] end)
|> Stream.map(fn [x, y] -> {x, y} end)
|> Stream.chunk_every(2, 1, :discard)
# |> (Enum.to_list() |> IO.inspect(label: "edges"))
|> Stream.map(&extract_coords_edge/1)
# |> (Enum.to_list() |> IO.inspect(label: "edges coords"))
|> Enum.reduce(&MapSet.union/2)
end
# one path is composed of one or more edges
def extract_coords_edge(edge) do
[node_start, node_end] = edge
extract_coords_nodes(node_start, node_end)
end
# one edge is described by exactly two nodes: node_start, node_end
def extract_coords_nodes({x1, same}, {x2, same}) do
Enum.to_list(x2..x1)
|> Stream.map(fn x -> {x, same} end)
|> MapSet.new()
end
def extract_coords_nodes({same, y1}, {same, y2}) do
Enum.to_list(y2..y1)
|> Stream.map(fn y -> {same, y} end)
|> MapSet.new()
end
end
Advent1.solve()
```
<!-- livebook:{"output":true} -->
```
MapSet.new([
{494, 9},
{495, 9},
{496, 6},
{496, 9},
{497, 6},
{497, 9},
{498, 4},
{498, 5},
{498, 6},
{498, 9},
{499, 9},
{500, 9},
{501, 9},
{502, 4},
{502, 5},
{502, 6},
{502, 7},
{502, 8},
{502, 9},
{503, 4}
])
```
