78 lines
1.7 KiB
C#
78 lines
1.7 KiB
C#
namespace aoc2021;
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/// <summary>
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/// Day 10: <see href="https://adventofcode.com/2021/day/10"/>
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/// </summary>
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public sealed class Day10 : Day
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{
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private static readonly Dictionary<char, char> MatchedBrackets = new()
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{
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{'(', ')'},
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{'[', ']'},
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{'{', '}'},
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{'<', '>'}
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};
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private static readonly Dictionary<char, long> Scores = new()
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{
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{ ')', 3 },
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{ ']', 57 },
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{ '}', 1197 },
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{ '>', 25137 }
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};
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private static readonly Dictionary<char, long> ScoresPart2 = new()
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{
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{ '(', 1 },
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{ '[', 2 },
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{ '{', 3 },
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{ '<', 4 }
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};
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private readonly long _score1;
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private readonly List<long> _scores2 = new();
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public Day10() : base(10, "Syntax Scoring")
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{
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_score1 = 0L;
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foreach (var line in Input)
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{
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var corrupt = false;
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var s = new Stack<char>();
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foreach (var c in line)
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{
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if (ScoresPart2.ContainsKey(c))
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{
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s.Push(c);
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}
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else
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{
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if (c == MatchedBrackets[s.Pop()]) continue;
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_score1 += Scores[c];
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corrupt = true;
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break;
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}
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}
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if (corrupt) continue;
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var score2 = 0L;
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while (s.Any())
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{
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score2 *= 5;
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score2 += ScoresPart2[s.Pop()];
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}
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_scores2.Add(score2);
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}
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}
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public override string Part1() => $"{_score1}";
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public override string Part2()
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{
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var sorted = _scores2.OrderBy(i => i).ToList();
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return $"{sorted[sorted.Count / 2]}";
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}
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}
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