From 97f0c2c506a977c311124524a379bfe236a50494 Mon Sep 17 00:00:00 2001
From: Yuri Leikind <yuri.leikind@gmail.com>
Date: Sun, 6 Dec 2015 16:03:14 +0100
Subject: [PATCH] char lists instead of UTF-8 encoded binaries a better fit for
 this task

---
 day1.ex | 38 ++++++++++++++++++++------------------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/day1.ex b/day1.ex
index b7ae079..258a3c3 100644
--- a/day1.ex
+++ b/day1.ex
@@ -27,16 +27,16 @@ defmodule Day1 do
 
   def floor(instructions), do: step(instructions, 0)
 
-  defp step("", floor), do: floor
-  defp step("(" <> instructions, floor), do: step(instructions, floor + 1)
-  defp step(")" <> instructions, floor), do: step(instructions, floor - 1)
+  defp step([], floor), do: floor
+  defp step( [?( | instructions], floor), do: step(instructions, floor + 1)
+  defp step( [?) | instructions], floor), do: step(instructions, floor - 1)
 
   def basement(instructions), do: step_basement(instructions, 0, 1)
 
-  defp step_basement("", _, _), do: 0
-  defp step_basement(")" <> _, 0, position), do: position
-  defp step_basement("(" <> instructions, floor, position), do: step_basement(instructions, floor + 1, position + 1)
-  defp step_basement(")" <> instructions, floor, position), do: step_basement(instructions, floor - 1, position + 1)
+  defp step_basement([], _, _), do: 0
+  defp step_basement([?) | _ ], 0, position), do: position
+  defp step_basement([?( | instructions], floor, position), do: step_basement(instructions, floor + 1, position + 1)
+  defp step_basement([?) | instructions], floor, position), do: step_basement(instructions, floor - 1, position + 1)
 
 end
 
@@ -47,28 +47,29 @@ defmodule Day1Test do
   use ExUnit.Case, async: true
 
   test "floor" do
-    assert 0 == Day1.floor("(())")
-    assert 0 == Day1.floor("()()")
+    assert 0 == Day1.floor('(())')
+    assert 0 == Day1.floor('()()')
 
-    assert 3 == Day1.floor("(((")
-    assert 3 == Day1.floor("(()(()(")
-    assert 3 == Day1.floor("))(((((")
+    assert 3 == Day1.floor('(((')
+    assert 3 == Day1.floor('(()(()(')
+    assert 3 == Day1.floor('))(((((')
 
-    assert -1 == Day1.floor("())")
-    assert -1 == Day1.floor("))(")
+    assert -1 == Day1.floor('())')
+    assert -1 == Day1.floor('))(')
 
-    assert -3 == Day1.floor(")))")
-    assert -3 == Day1.floor(")())())")
+    assert -3 == Day1.floor(')))')
+    assert -3 == Day1.floor(')())())')
   end
 
   test "basement" do
-    assert 1 == Day1.basement(")")
-    assert 5 == Day1.basement("()())")
+    assert 1 == Day1.basement(')')
+    assert 5 == Day1.basement('()())')
   end
 
   test "input floor" do
     IO.puts "floor"
     File.read!("day1.txt")
+    |> to_char_list
     |> Day1.floor
     |> IO.puts
   end
@@ -76,6 +77,7 @@ defmodule Day1Test do
   test "input basement" do
     IO.puts "basement"
     File.read!("day1.txt")
+    |> to_char_list
     |> Day1.basement
     |> IO.puts
   end