I guess it was time for formatting

day1.exs

@@ -1,27 +1,32 @@
 defmodule DayOne do
   def part_one(input) do
     String.split(input, "\n")
-          |> Enum.map(&DayOne.parseNum/1)
-          |> List.foldr(0, &(&1 + &2))
+    |> Enum.map(&DayOne.parseNum/1)
+    |> List.foldr(0, &(&1 + &2))
   end
 
-  def part_two(input), do: partTwo(String.split(input, "\n") |> Enum.map(&DayOne.parseNum/1), 0, [])
+  def part_two(input),
+    do: partTwo(String.split(input, "\n") |> Enum.map(&DayOne.parseNum/1), 0, [])
 
-  def part_two(input, acc , frequencies) do
+  def part_two(input, acc, frequencies) do
     [head | tail] = input
     freq = head + acc
     # IO.puts("Got frequency #{freq}")
-    if Enum.member?(frequencies, freq), do: freq, else: partTwo(tail ++ [head], freq, [freq | frequencies])
+    if Enum.member?(frequencies, freq),
+      do: freq,
+      else: partTwo(tail ++ [head], freq, [freq | frequencies])
   end
 
-  def parse_num("+" <> num) do 
+  def parse_num("+" <> num) do
     {intVal, ""} = Integer.parse(num)
     intVal
   end
+
   def parse_num("-" <> num) do
     {intVal, ""} = Integer.parse(num)
     0 - intVal
   end
+
   def parse_num(num) do
     IO.puts(num)
     0

day2.exs

@@ -1,39 +1,47 @@
 defmodule DayTwo do
-
   def part_one(input) do
     lines = String.split(input, "\n") |> Enum.map(&String.codepoints/1)
-    two = Enum.map(lines, fn string -> DayTwo.check_occurence(string, 2) end)
-      |> Enum.filter(&(&1))
-    three = Enum.map(lines, fn string -> DayTwo.check_occurence(string, 3) end)
-      |> Enum.filter(&(&1))
+
+    two =
+      Enum.map(lines, fn string -> DayTwo.check_occurence(string, 2) end)
+      |> Enum.filter(& &1)
+
+    three =
+      Enum.map(lines, fn string -> DayTwo.check_occurence(string, 3) end)
+      |> Enum.filter(& &1)
+
     length(two) * length(three)
   end
 
-  def check_occurence(line, req) do 
-    size = Enum.reduce(line, %{}, fn x, acc -> Map.update(acc, x, 1, &(&1 + 1)) end)
-        |> Enum.into([])
-        |> Enum.filter(fn {_, count} -> count == req end)
-        |> length
+  def check_occurence(line, req) do
+    size =
+      Enum.reduce(line, %{}, fn x, acc -> Map.update(acc, x, 1, &(&1 + 1)) end)
+      |> Enum.into([])
+      |> Enum.filter(fn {_, count} -> count == req end)
+      |> length
+
     size > 0
   end
 
   def part_two(input) do
     lines = String.split(input, "\n") |> Enum.map(&String.codepoints/1)
+
     Enum.map(lines, fn line ->
-      Enum.map(lines, fn linetwo -> 
+      Enum.map(lines, fn linetwo ->
         diff = compare_strings(line, linetwo)
+
         if diff == 1 do
           IO.puts("#{line} #{linetwo}")
         end
       end)
     end)
+
     nil
   end
 
   def compare_strings(one, two) do
     Enum.zip(one, two)
-        |> Enum.filter(fn {one, two} -> one != two end)
-        |> length
+    |> Enum.filter(fn {one, two} -> one != two end)
+    |> length
   end
-
 end

day3.exs

@@ -1,47 +1,60 @@
 defmodule DayThree do
-
   def parse_claim(claim) do
     pattern = ~r/#(\d+) @ (\d+),(\d+): (\d+)x(\d+)/
-    [ [ _ | match ] ] = Regex.scan(pattern, claim)
-    [id, x, y, xwidth, ywidth] = Enum.map(match, &(String.to_integer(&1)))
+    [[_ | match]] = Regex.scan(pattern, claim)
+    [id, x, y, xwidth, ywidth] = Enum.map(match, &String.to_integer(&1))
 
     {id, x, y, xwidth, ywidth}
   end
 
   def part_one(input) do
-    claims = String.split(input, "\n")
+    claims =
+      String.split(input, "\n")
       |> Enum.filter(&(&1 != ""))
       |> Enum.map(&DayThree.parse_claim/1)
-    IO.puts "dupes"
+
     dupes = new_doubles(claims)
-      |> Enum.dedup
-    area_with = dupes
+
+    area_with =
+      dupes
       |> Enum.map(fn {_, {_, _, dx, dy}} -> dx * dy end)
       |> List.foldl(0, &+/2)
+
     area_with
   end
 
   def new_doubles(claims) do
     Enum.map(claims, fn {id1, x1, y1, dx1, dy1} ->
       Enum.map(claims, fn {id2, x2, y2, dx2, dy2} ->
-        {{:id, id1, id2}, intersect({x1, y1, dx1, dy1}, {x2, y2, dx2, dy2})}
-      end) |> Enum.filter(fn {_, square} -> square != nil end)
-    end)
-      |> List.flatten
+        {{:id, id1, id2}, intersect({id1, x1, y1, dx1, dy1}, {id2, x2, y2, dx2, dy2})}
+      end)
       |> Enum.filter(fn {_, square} -> square != nil end)
+    end)
+    |> List.flatten()
+    |> Enum.filter(fn {_, square} -> square != nil end)
   end
 
-  def intersect({x1, y1, dx1, dy1}, {x2, y2, dx2, dy2}) do
-    if {x1, y1, dx1, dy1} == {x2, y2, dx2, dy2} do
+  def intersect({id1, x1, y1, dx1, dy1}, {id2, x2, y2, dx2, dy2}) do
+    if id1 == id2 do
+      nil
+    else
+      intersect({x1, y1, dx1, dy1}, {x2, y2, dx2, dy2}, true)
+    end
+  end
+
+  def intersect({x1, y1, dx1, dy1}, {x2, y2, dx2, dy2}, ignore \\ false) do
+    if {x1, y1, dx1, dy1} == {x2, y2, dx2, dy2} && not ignore do
       nil
     else
       xe1 = x1 + dx1
       xe2 = x2 + dx2
       ye1 = y1 + dy1
+
       if x2 <= xe1 && y2 <= ye1 && x2 >= x1 && y2 >= y1 do
         {y2, x2, xe1 - x2, ye1 - y2}
-      else if xe2 >= x1 && y2 <= ye1 && x2 <= x1 && y2 >= y1 do
-        {x1, y2, xe2 - x1, ye1 - y2}
+      else
+        if xe2 >= x1 && y2 <= ye1 && x2 <= x1 && y2 >= y1 do
+          {x1, y2, xe2 - x1, ye1 - y2}
         else
           nil
         end
@@ -50,21 +63,24 @@ defmodule DayThree do
   end
 
   def part_two(input) do
-    claims = String.split(input, "\n")
+    claims =
+      String.split(input, "\n")
       |> Enum.filter(&(&1 != ""))
       |> Enum.map(&DayThree.parse_claim/1)
-    IO.puts "dupes"
-    dupes = new_doubles(claims)
-      |> Enum.dedup
+
+    dupes =
+      new_doubles(claims)
+      |> Enum.dedup()
       |> Enum.map(fn {{:id, id1, id2}, _} -> [id1, id2] end)
-      |> List.flatten
+      |> List.flatten()
+
     claim_id = Enum.map(claims, fn {id, _, _, _, _} -> id end)
     [id] = Enum.filter(claim_id, &(not Enum.member?(dupes, &1)))
     id
   end
 end
 
-{:ok, content} = File.read "input3.txt"
+{:ok, content} = File.read("input3.txt")
 
-IO.puts "Part 1: #{DayThree.part_one(content)}"
-IO.puts "Part 2: #{DayThree.part_two(content)}"
+IO.puts("Part 1 (most likely incorrect): #{DayThree.part_one(content)}")
+IO.puts("Part 2: #{DayThree.part_two(content)}")