Day Two

day02.livemd

@@ -0,0 +1,77 @@
+# Day02
+
+```elixir
+Mix.install([
+  {:kino, "~> 0.14.2"},
+])
+```
+
+## Run Me
+
+[![Run in Livebook](https://livebook.dev/badge/v1/blue.svg)](https://livebook.dev/run?url=https%3A%2F%2Fgit.kev.pub%2Fkev%2Faoc2024%2Fraw%2Fbranch%2Fmain%2Fday01.livemd)
+
+## Input
+
+```elixir
+input = Kino.Input.textarea("Input")
+```
+
+## Part One
+
+```elixir
+defmodule PartOne do
+  def differences([_]), do: []
+  def differences([a, b|t]), do: [a - b| differences([b|t])]
+
+  def parse(input) do
+    input 
+    |> Kino.Input.read
+    |> String.split("\n")
+    |> Enum.map(fn l -> l |> String.split(" ")|> Enum.map(&String.to_integer/1) end)
+  end
+
+  def pass_diffs(l) do
+    fail = l
+    |> PartOne.differences
+    |> Enum.any?(fn y -> (abs(y) > 3 || y == 0) end)
+
+    !fail
+  end
+
+  def pass_direction(l) do
+    l = 
+      l
+      |> PartOne.differences
+      |> Enum.map(fn x -> x > 0 end)
+      |> Enum.dedup
+      |> length
+    
+    l == 1
+  end
+
+  def passes(x), do: pass_diffs(x) && pass_direction(x)
+end
+
+input
+|> PartOne.parse
+|> Enum.count(&PartOne.passes/1)
+
+```
+
+## Part Two
+
+```elixir
+%{false: fails, true: passes} = 
+  input
+  |> PartOne.parse
+  |> Enum.group_by(&PartOne.passes/1)
+
+fail_count = Enum.map(fails, fn l -> 
+  0..length(l)
+  |> Enum.map(fn x -> List.delete_at(l,x) end)
+  |> Enum.any?(&PartOne.passes/1)
+end)
+|> Enum.count(fn x -> x end)
+
+length(passes) + fail_count
+```