94 lines
3.1 KiB
C#
94 lines
3.1 KiB
C#
using MoreLinq;
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namespace AOC2022;
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/// <summary>
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/// Day 11: <a href="https://adventofcode.com/2022/day/11"/>
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/// </summary>
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public sealed class Day11() : Day(2022, 11, "Monkey in the Middle")
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{
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private Monkey[]? _monkeys;
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private long _lcm;
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public override void ProcessInput()
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{
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_monkeys = Input.Split("").Select(Monkey.FromLines).ToArray();
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_lcm = _monkeys!.Aggregate(1L, (i, monkey) => i * monkey.ModTest);
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}
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private void DoRound(bool part1 = true)
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{
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foreach (var monkey in _monkeys!)
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{
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while (monkey.Items.Count != 0)
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{
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var item = monkey.Items.Dequeue();
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item = monkey.Operation(item);
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if (part1) item /= 3;
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item %= _lcm;
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monkey.InspectionCount++;
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var dest = item % monkey.ModTest == 0 ? monkey.TrueDest : monkey.FalseDest;
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_monkeys[dest].Items.Enqueue(item);
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}
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}
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}
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private long MonkeyBusiness() =>
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_monkeys!.OrderByDescending(m => m.InspectionCount).Take(2)
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.Aggregate(1L, (i, monkey) => i * monkey.InspectionCount);
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public override object Part1()
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{
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Enumerable.Range(0, 20).ForEach(_ => DoRound());
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return MonkeyBusiness();
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}
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public override object Part2()
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{
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ProcessInput();
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Enumerable.Range(0, 10_000).ForEach(_ => DoRound(part1: false));
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return MonkeyBusiness();
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}
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private class Monkey
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{
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public Queue<long> Items { get; private set; } = new();
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public Func<long, long> Operation { get; private set; } = _ => 0L;
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public long ModTest { get; private set; }
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public int TrueDest { get; private set; }
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public int FalseDest { get; private set; }
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public long InspectionCount { get; set; }
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public static Monkey FromLines(IEnumerable<string> lines)
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{
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var m = new Monkey();
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foreach (var line in lines.Select(l => l.Trim()))
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{
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if (line.StartsWith("Starting items: "))
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m.Items = new(line.Split("Starting items: ")[1].Split(", ").Select(long.Parse));
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else if (line.StartsWith("Operation: "))
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{
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var s = line.Split("Operation: new = old ")[1];
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if (long.TryParse(s[2..], out var amount))
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m.Operation = s[0] switch
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{
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'*' => i => i * amount,
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'+' => i => i + amount,
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_ => throw new ArgumentOutOfRangeException(line, "invalid operation")
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};
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else m.Operation = i => i * i;
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}
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else if (line.StartsWith("Test: "))
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m.ModTest = long.Parse(line.Split("Test: divisible by ")[1]);
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else if (line.StartsWith("If true: "))
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m.TrueDest = int.Parse(line.Split(' ')[5]);
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else if (line.StartsWith("If false: "))
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m.FalseDest = int.Parse(line.Split(' ')[5]);
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}
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return m;
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}
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}
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}
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