Complete Day 1 2023

lib/advent_2023/day_01.ex

@@ -1,9 +1,14 @@
 defmodule Advent2023.Day01 do
   def calibration_value(input) do
-    digit_string = digits(input)
+    input
+    |> digits_only()
+    |> first_last()
+  end
 
-    "#{String.first(digit_string)}#{String.last(digit_string)}"
-    |> String.to_integer()
+  def calibration_value_with_words(input) do
+    input
+    |> digits_with_words()
+    |> first_last()
   end
 
   def calibration_sum(lines) do
@@ -13,10 +18,46 @@ defmodule Advent2023.Day01 do
     |> Enum.sum()
   end
 
-  defp digits(str) do
-    str
-    |> String.to_charlist()
-    |> Enum.filter(fn x -> x in ?0..?9 end)
-    |> List.to_string()
+  def calibration_sum_with_words(lines) do
+    lines
+    |> String.split("\n", trim: true)
+    |> Enum.map(&calibration_value_with_words/1)
+    |> Enum.sum()
+  end
+
+  defp digits_only(str) do
+    Regex.scan(~r{[1-9]}, str)
+    |> List.flatten()
+  end
+
+  defp digits_with_words(str) do
+    Regex.scan(~r{\d|oneight|twone|eightwo|nineight|eighthree|one|two|three|four|five|six|seven|eight|nine}, str)
+    |> Enum.map(&to_digits/1)
+    |> List.flatten()
+  end
+
+  defp first_last(list) do
+    "#{List.first(list)}#{List.last(list)}"
+    |> String.to_integer()
+  end
+
+  defp to_digits([str]) do
+    case str do
+      "oneight" -> [1, 8]
+      "twone" -> [2, 1]
+      "eightwo" -> [8, 2]
+      "nineight" -> [9, 8]
+      "eighthree" -> [8, 3]
+      "one" -> 1
+      "two" -> 2
+      "three" -> 3
+      "four" -> 4
+      "five" -> 5
+      "six" -> 6
+      "seven" -> 7
+      "eight" -> 8
+      "nine" -> 9
+      _ -> String.to_integer(str)
+    end
   end
 end

test/lib/advent_2023/day_01_test.exs

@@ -19,6 +19,28 @@ defmodule Advent2023.Day01Test do
     assert Day01.calibration_sum(input) == 55_834
   end
 
+  test "calibration_value_with_words" do
+    assert Day01.calibration_value_with_words("pqr3stu8vwx") == 38
+    assert Day01.calibration_value_with_words("4nineeightseven2") == 42
+    assert Day01.calibration_value_with_words("xtwone3four") == 24
+    assert Day01.calibration_value_with_words("7pqrstsixteen") == 76
+    assert Day01.calibration_value_with_words("6huhoneight") == 68
+    assert Day01.calibration_value_with_words("twone") == 21
+    assert Day01.calibration_value_with_words("eightwo") == 82
+    assert Day01.calibration_value_with_words("nineight") == 98
+    assert Day01.calibration_value_with_words("eighthree") == 83
+  end
+
+  test "calibration_sum_with_words" do
+    assert Day01.calibration_sum_with_words(input_words()) == 281
+    assert Day01.calibration_sum_with_words(input()) == 142
+  end
+
+  test "calibration_sum_with_words real" do
+    input = File.read!("test/lib/advent_2023/input/day_01.txt")
+    assert Day01.calibration_sum_with_words(input) == 53_221
+  end
+
   defp input do
     """
     1abc2
@@ -27,4 +49,16 @@ defmodule Advent2023.Day01Test do
     treb7uchet
     """
   end
+
+  defp input_words do
+    """
+    two1nine
+    eightwothree
+    abcone2threexyz
+    xtwone3four
+    4nineeightseven2
+    zoneight234
+    7pqrstsixteen
+    """
+  end
 end