D1: More concise and somehow faster...

Author: Formula-9

Solutions/Day01/Day01.cs

@@ -1,11 +1,15 @@
-using System.Collections.Immutable;
 using Formula9.AdventOfCode.Utils;
 
 namespace Formula9.AdventOfCode.Solutions2023.Day01;
 
 public class Day_01 : AdventOfCodeProblem
 {
- public Day_01() : base(2023, 1) { }
+ private string[] SplitInput { get; init; }
+
+ public Day_01() : base(2023, 1) 
+ { 
+ SplitInput = Input.SplitByNewline();
+ }
 
  private static readonly IDictionary<string, string> Digits = new Dictionary<string, string>()
  {
@@ -18,17 +22,13 @@ public Day_01() : base(2023, 1) { }
  { "seven", "s7n" },
  { "eight", "e8t" },
  { "nine", "n9e" }
- }.ToImmutableDictionary();
+ };
 
- private static int FindDigitPair(string s)
- {
- string altered = s.ReplaceAll(Digits);
- char first = altered.First(char.IsDigit);
- char last = altered.Last(char.IsDigit);
- return (first - '0') * 10 + (last - '0');
- }
+ private static int FindDigitPair(string s) => SumFirstAndLastDigit(s.ReplaceAll(Digits));
+
+ private static int SumFirstAndLastDigit(string s) => (s.First(char.IsDigit) - '0') * 10 + (s.Last(char.IsDigit) - '0');
 
- public override ValueTask<string> Solve_1() => new(Input.SplitByNewline().Select(l => int.Parse(new char[] { l.First(char.IsDigit), l.Last(char.IsDigit) })).Sum().ToString());
+ public override ValueTask<string> Solve_1() => new(SplitInput.Select(SumFirstAndLastDigit).Sum().ToString());
 
- public override ValueTask<string> Solve_2() => new(Input.SplitByNewline().Select(FindDigitPair).Sum().ToString());
+ public override ValueTask<string> Solve_2() => new(SplitInput.Select(FindDigitPair).Sum().ToString());
 }