Day 11 solution

Prime number shenanigans...I do not like "cool math games"...

advent-of-code-2022.csproj

@@ -54,6 +54,7 @@
 	  <EmbeddedResource Include="inputs\10b.txt" />
 	  <EmbeddedResource Include="inputs\11.txt" />
 	  <None Remove="inputs\12.txt" />
+	  <EmbeddedResource Include="inputs\11a.txt" />
 	  <EmbeddedResource Include="inputs\12.txt" />
 	  <None Remove="inputs\13.txt" />
 	  <EmbeddedResource Include="inputs\13.txt" />

inputs/11.txt

@@ -1,10 +1,55 @@
-3265255276
-1537412665
-7335746422
-6426325658
-3854434364
-8717377486
-4522286326
-6337772845
-8824387665
-6351586484
+Monkey 0:
+  Starting items: 62, 92, 50, 63, 62, 93, 73, 50
+  Operation: new = old * 7
+  Test: divisible by 2
+    If true: throw to monkey 7
+    If false: throw to monkey 1
+
+Monkey 1:
+  Starting items: 51, 97, 74, 84, 99
+  Operation: new = old + 3
+  Test: divisible by 7
+    If true: throw to monkey 2
+    If false: throw to monkey 4
+
+Monkey 2:
+  Starting items: 98, 86, 62, 76, 51, 81, 95
+  Operation: new = old + 4
+  Test: divisible by 13
+    If true: throw to monkey 5
+    If false: throw to monkey 4
+
+Monkey 3:
+  Starting items: 53, 95, 50, 85, 83, 72
+  Operation: new = old + 5
+  Test: divisible by 19
+    If true: throw to monkey 6
+    If false: throw to monkey 0
+
+Monkey 4:
+  Starting items: 59, 60, 63, 71
+  Operation: new = old * 5
+  Test: divisible by 11
+    If true: throw to monkey 5
+    If false: throw to monkey 3
+
+Monkey 5:
+  Starting items: 92, 65
+  Operation: new = old * old
+  Test: divisible by 5
+    If true: throw to monkey 6
+    If false: throw to monkey 3
+
+Monkey 6:
+  Starting items: 78
+  Operation: new = old + 8
+  Test: divisible by 3
+    If true: throw to monkey 0
+    If false: throw to monkey 7
+
+Monkey 7:
+  Starting items: 84, 93, 54
+  Operation: new = old + 1
+  Test: divisible by 17
+    If true: throw to monkey 2
+    If false: throw to monkey 1

inputs/11a.txt

@@ -0,0 +1,27 @@
+Monkey 0:
+  Starting items: 79, 98
+  Operation: new = old * 19
+  Test: divisible by 23
+    If true: throw to monkey 2
+    If false: throw to monkey 3
+
+Monkey 1:
+  Starting items: 54, 65, 75, 74
+  Operation: new = old + 6
+  Test: divisible by 19
+    If true: throw to monkey 2
+    If false: throw to monkey 0
+
+Monkey 2:
+  Starting items: 79, 60, 97
+  Operation: new = old * old
+  Test: divisible by 13
+    If true: throw to monkey 1
+    If false: throw to monkey 3
+
+Monkey 3:
+  Starting items: 74
+  Operation: new = old + 3
+  Test: divisible by 17
+    If true: throw to monkey 0
+    If false: throw to monkey 1

src/11.cs

@@ -0,0 +1,131 @@
+namespace aoc2022;
+
+internal class Day11 : Day
+{
+    private class monkey
+    {
+        public readonly Queue<long> startingItems = new();
+        public Queue<long> items = new();
+        public string operation = string.Empty;
+        public long testDivBy;
+        public int trueTarget;
+        public int falseTarget;
+        public long timesInspected;
+    }
+
+    private readonly List<monkey> monkeys = new();
+    private long divideByProduct = 1;
+
+    internal override void Parse()
+    {
+        monkey? m = null;
+        foreach (var line in Util.Parsing.ReadAllLines("11"))
+        {
+            if (line.StartsWith("Monkey"))
+            {
+                m = new monkey();
+                monkeys.Add(m);
+            }
+            else if (line.Trim().StartsWith("Starting items"))
+            {
+                var parts = line.Split(':');
+                var items = parts[1].Split(',');
+                foreach (var item in items)
+                {
+                    m!.startingItems.Enqueue(int.Parse(item.Trim()));
+                }
+            }
+            else if (line.Trim().StartsWith("Operation"))
+            {
+                m!.operation = line.Split(':')[1].Trim()["new = ".Length..];
+            }
+            else if (line.Trim().StartsWith("Test"))
+            {
+                m!.testDivBy = int.Parse(line.Trim().Split(' ')[3]);
+                divideByProduct *= m.testDivBy;
+            }
+            else if (line.Trim().StartsWith("If true"))
+            {
+                m!.trueTarget = int.Parse(line.Trim().Split(' ')[5]);
+            }
+            else if (line.Trim().StartsWith("If false"))
+            {
+                m!.falseTarget = int.Parse(line.Trim().Split(' ')[5]);
+            }
+        }
+    }
+
+    private void monkeyRound(Func<long, long> worryReducer)
+    {
+        foreach (var m in monkeys)
+        {
+            while (m.items.Count > 0)
+            {
+                long item = m.items.Dequeue();
+
+                long[] operands = new long[2];
+                var op = m.operation.Replace("old", $"{item}");
+                var parts = op.Split(' ');
+                operands[0] = long.Parse(parts.First());
+                operands[1] = long.Parse(parts.Last());
+                if (m.operation.Contains('*'))
+                {
+                    item = operands[0] * operands[1];
+                }
+                else
+                {
+                    item = operands[0] + operands[1];
+                }
+
+                item = worryReducer(item);
+
+                if (item % m.testDivBy == 0)
+                {
+                    monkeys[m.trueTarget].items.Enqueue(item);
+                }
+                else
+                {
+                    monkeys[m.falseTarget].items.Enqueue(item);
+                }
+
+                m.timesInspected++;
+            }
+        }
+    }
+
+    internal override string Part1()
+    {
+        monkeys.ForEach(m =>
+        {
+            m.timesInspected = 0;
+            m.items = new(m.startingItems);
+        });
+        for (int round = 0; round < 20; round++)
+        {
+            monkeyRound(worry => worry / 3);
+        }
+
+        var sorted = monkeys.OrderByDescending(m => m.timesInspected);
+        var monkeyBusiness = sorted.Take(2).Aggregate(1L, (x, y) => x * y.timesInspected);
+        return $"Monkey business after 20 rounds, dividing worry by 3: <+white>{monkeyBusiness}";
+    }
+
+    internal override string Part2()
+    {
+        // still hurting for a deep copy utility...
+        monkeys.ForEach(m =>
+        {
+            m.timesInspected = 0;
+            m.items = new(m.startingItems);
+        });
+
+        for (int round = 0; round < 10000; round++)
+        {
+            monkeyRound(worry => worry % divideByProduct);
+        }
+
+        var sorted = monkeys.OrderByDescending(m => m.timesInspected);
+        var monkeyBusiness = sorted.Take(2).Aggregate(1L, (x, y) => x * y.timesInspected);
+        return $"Monkey business after 10,000 rounds, reducing worry 'another way': <+white>{monkeyBusiness}";
+    }
+}