40 lines
1.3 KiB
C#
40 lines
1.3 KiB
C#
namespace AOC2015;
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/// <summary>
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/// Day 5: <a href="https://adventofcode.com/2015/day/5"/>
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/// </summary>
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public sealed partial class Day05() : Day(2015, 5, "Doesn't He Have Intern-Elves For This?")
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{
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private static readonly List<char> Vowels = ['a', 'e', 'i', 'o', 'u'];
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private List<string> _strings = [];
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[GeneratedRegex(@"(.)\1")]
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private static partial Regex DoubleLetter();
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[GeneratedRegex(@"(.).\1")]
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private static partial Regex LetterSandwich();
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[GeneratedRegex(@"(..).*\1")]
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private static partial Regex TwoPairs();
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public override void ProcessInput() =>
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_strings = Input.Where(line => !string.IsNullOrEmpty(line)).ToList();
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public override object Part1() =>
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_strings.Count(s =>
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{
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// bad substrings
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if (s.Contains("ab") || s.Contains("cd") || s.Contains("pq") || s.Contains("xy"))
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return false;
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// must have at least 3 vowels
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if (s.Count(c => Vowels.Contains(c)) < 3) return false;
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// must have a double-letter somewhere
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return DoubleLetter().Matches(s).Count >= 1;
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});
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public override object Part2() =>
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_strings.Count(s => LetterSandwich().Matches(s).Count >= 1 && TwoPairs().Matches(s).Count == 1);
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}
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