51 lines
1.2 KiB
C#
51 lines
1.2 KiB
C#
using System.Linq;
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namespace aoc2019
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{
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internal sealed class Day4 : Day
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{
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private readonly int end;
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private readonly int start;
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public Day4()
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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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public override int DayNumber => 4;
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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 c in i.ToString())
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{
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var curr = c - '0';
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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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{
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return $"{Enumerable.Range(start, end).Count(IsValid)}";
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}
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public override string Part2()
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{
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return $"{Enumerable.Range(start, end).Count(HasOnePair)}";
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}
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}
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} |