<!-- livebook:{"file_entries":[{"name":"day3_1.txt","type":"attachment"}]} -->
# Day 3
```elixir
Mix.install([
{:kino, "~> 0.13.0"}
])
```
## Part 1
```elixir
content =
Kino.FS.file_path("day3_1.txt")
|> File.read!()
|> String.trim()
```
```elixir
defmodule MulParser do
def scan_mul(input) do
Regex.scan(~r/mul\(\d{1,3}[,]\d{1,3}\)/, input)
|> List.flatten()
# For each mul expression -> Get the two integers
|> Enum.map(fn line ->
Regex.scan(~r/\d{1,3}/, line)
|> List.flatten()
|> Enum.map(fn n -> String.to_integer(n) end)
# Multiply the integers
|> Enum.reduce(fn x, acc -> x * acc end)
end)
# Sum for result
|> Enum.sum()
end
end
MulParser.scan_mul(content)
```
## Part 2
```elixir
# For this one we will use the same scan_mul in sections where it is enabled
defmodule Conditional do
def split_at_first_occurrence(string, delimiter) do
# Split the string at the delimiter, with only 2 parts so that it splits at first occurence
parts = String.split(string, delimiter, parts: 2)
# Return the parts as a tuple
case parts do
[head, tail] -> {head, tail}
# If the delimiter is not found, return the original string and an empty string
_ -> {string, ""}
end
end
def compute(input, result, computing) do
case computing do
:do ->
# Split head and tail
{head, tail} = Conditional.split_at_first_occurrence(input, "don't()")
# Compute result, if there is nothing left, return result
if tail == "" do
MulParser.scan_mul(head) + result
else
# Else compute the tail as well
compute(tail, MulParser.scan_mul(head) + result, :dont)
end
:dont ->
# On don't case we just ignore the head and goto tail
{_head, tail} = Conditional.split_at_first_occurrence(input, "do()")
if tail == "" do
result
else
compute(tail, result, :do)
end
end
end
end
Conditional.compute(content, 0, :do)
```
