40 lines
998 B
C#
40 lines
998 B
C#
namespace AOC2019;
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public sealed class Day04 : Day
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{
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private readonly int _start, _end;
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public Day04() : base(2019, 4, "Secure Container")
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{
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var range = Input.First().Split('-').Select(int.Parse).ToList();
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_start = range[0];
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_end = range[1];
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}
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private bool IsValid(int i)
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{
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var prev = 0;
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var hasDup = false;
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foreach (var curr in i.ToString().Select(c => c - '0'))
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{
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if (curr < prev) return false;
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if (curr == prev) hasDup = true;
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prev = curr;
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}
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return i >= _start && i <= _end && hasDup;
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}
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private bool HasOnePair(int i)
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{
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var s = i.ToString();
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return IsValid(i) && s.Select(c => s.Count(j => j == c)).Any(c => c == 2);
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}
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public override string Part1() =>
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$"{Enumerable.Range(_start, _end).Count(IsValid)}";
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public override string Part2() =>
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$"{Enumerable.Range(_start, _end).Count(HasOnePair)}";
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}
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