47 lines
1.2 KiB
C#
47 lines
1.2 KiB
C#
namespace AOC2020;
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/// <summary>
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/// Day 2: <a href="https://adventofcode.com/2020/day/1" />
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/// </summary>
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public sealed class Day02() : Day(2020, 2, "Password Philosophy")
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{
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private ImmutableList<Password>? _passwords;
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public override void ProcessInput() =>
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_passwords = Input.Select(p => new Password(p)).ToImmutableList();
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public override object Part1() =>
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_passwords!.Count(p => p.IsValid);
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public override object Part2() =>
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_passwords!.Count(p => p.IsValidByIndex);
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private class Password
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{
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public Password(string line)
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{
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var split = line.Split(": ", 2);
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var split2 = split[0].Split(' ', 2);
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var indices = split2[0].Split('-', 2);
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I = int.Parse(indices[0]);
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J = int.Parse(indices[1]);
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C = char.Parse(split2[1]);
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Value = split[1];
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}
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public bool IsValid =>
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Count >= I && Count <= J;
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public bool IsValidByIndex =>
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(Value[I - 1] == C) ^ (Value[J - 1] == C);
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private int Count =>
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Value.Count(p => p == C);
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private int I { get; }
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private int J { get; }
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private char C { get; }
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private string Value { get; }
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}
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}
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