# Day 03
## Setup
```elixir
Mix.install([{:kino, "~> 0.4.0"}])
```
```elixir
example_input = Kino.Input.textarea("example data:")
```
```elixir
real_input = Kino.Input.textarea("real data:")
```
## Part 1
```elixir
example_input
|> Kino.Input.read()
|> String.split("\n", trim: true)
|> Enum.map(&String.split(&1, "", trim: true))
|> Enum.zip()
|> Enum.map(&Enum.frequencies(Tuple.to_list(&1)))
|> Enum.reduce(["", ""], fn
%{"0" => zero, "1" => one}, [gamma, epsilon] ->
if zero > one, do: [gamma <> "0", epsilon <> "1"], else: [gamma <> "1", epsilon <> "0"]
end)
|> Enum.map(&String.to_integer(&1, 2))
|> Enum.reduce(&Kernel.*(&1, &2))
```
## Part 2
```elixir
defmodule Filter do
def filter(input, pred, match), do: filter(input, pred, match, 0, length(Enum.at(input, 0)))
defp filter([filtered], _pred, _match, _at, _len), do: [filtered]
defp filter(filtered, _pred, _match, at, at), do: filtered
defp filter(filtered, pred, match, at, len) do
filtered
|> Enum.map(&Enum.at(&1, at))
|> Enum.frequencies()
|> Map.values()
|> then(&filter(filtered, pred, match, at, len, &1))
end
defp filter(filtered, pred, match, at, len, [same, same]) do
Enum.filter(filtered, &(Enum.at(&1, at) == match))
|> filter(pred, match, at + 1, len)
end
defp filter(filtered, pred, match, at, len, [_only]) do
Enum.filter(filtered, &(Enum.at(&1, at) == match))
|> filter(pred, match, at + 1, len)
end
defp filter(filtered, pred, match, at, len, [zero, one]) do
filtered =
if pred.(zero, one) do
Enum.filter(filtered, &(Enum.at(&1, at) == "0"))
else
Enum.filter(filtered, &(Enum.at(&1, at) == "1"))
end
filter(filtered, pred, match, at + 1, len)
end
end
real_input
|> Kino.Input.read()
|> String.split("\n", trim: true)
|> Enum.map(&String.split(&1, "", trim: true))
|> then(fn input ->
[
Filter.filter(input, &Kernel.>/2, "1")
|> Enum.map(&Enum.join/1)
|> Enum.map(&String.to_integer(&1, 2)),
Filter.filter(input, &Kernel.</2, "0")
|> Enum.map(&Enum.join/1)
|> Enum.map(&String.to_integer(&1, 2))
]
end)
|> List.flatten()
|> Enum.reduce(&Kernel.*(&1, &2))
```
