day 19 part 1

AdventOfCode/Day19.cs

@@ -0,0 +1,130 @@
+using System.Text.RegularExpressions;
+
+namespace AdventOfCode;
+
+public class Day19 : BaseDay
+{
+    private Dictionary<string, Workflow> _workflows;
+    private Part[] _parts;
+
+    public Day19()
+    {
+        string lines = File.ReadAllText(InputFilePath);
+        string[] sections = lines.Split(Environment.NewLine + Environment.NewLine);
+
+        string[] workflows = sections[0].Split(Environment.NewLine);
+        _workflows = new Dictionary<string, Workflow>();
+        for (int i = 0; i < workflows.Length; ++i)
+        {
+            string[] wfParts = workflows[i].Split("{");
+            string wfName = wfParts[0];
+            string[] r = wfParts[1].Replace("}", "").Split(",");
+
+            Rule[] rules = new Rule[r.Length];
+            for (int j = 0; j < rules.Length; ++j)
+            {
+                string[] ruleParts = r[j].Split(":");
+                Condition condition = null;
+                if (ruleParts.Length == 2)
+                {
+                    condition = new Condition(ruleParts[0][0], ruleParts[0][1], int.Parse(ruleParts[0].Substring(2)));
+                }
+
+                rules[j] = new Rule(condition, ruleParts.Length == 2 ? ruleParts[1] : ruleParts[0]);
+            }
+
+            _workflows[wfName] = new Workflow(wfName, rules);
+        }
+
+        string[] parts = sections[1].Split(Environment.NewLine);
+        _parts = new Part[parts.Length];
+        for (int i = 0; i < parts.Length; ++i)
+        {
+            Match match = Regex.Match(parts[i], "{x=(\\d+),m=(\\d+),a=(\\d+),s=(\\d+)}");
+            _parts[i] = new Part(
+                int.Parse(match.Groups[1].Value),
+                int.Parse(match.Groups[2].Value),
+                int.Parse(match.Groups[3].Value),
+                int.Parse(match.Groups[4].Value)
+            );
+        }
+    }
+
+    public override ValueTask<string> Solve_1()
+    {
+        int sum = _parts.Where(part => IsAccepted(part)).Select(part => part.Sum()).Sum();
+        return new(sum.ToString());
+    }
+
+    public override ValueTask<string> Solve_2()
+    {
+        return new("TBD");
+    }
+
+    private bool IsAccepted(Part part, string workflow = "in")
+    {
+        Workflow current = _workflows[workflow];
+
+        foreach (Rule rule in current.Rules)
+        {
+            if (IsConditionMet(rule.Condition, part))
+            {
+                if (rule.Result == "R")
+                {
+                    return false;
+                }
+                else if (rule.Result == "A")
+                {
+                    return true;
+                }
+                else
+                { 
+                    return IsAccepted(part, rule.Result);
+                }
+            }
+        }
+
+        throw new NotImplementedException();
+    }
+
+    private bool IsConditionMet(Condition condition, Part part)
+    {
+        if (condition == null)
+        {
+            return true;
+        }
+
+        switch ((condition.Property, condition.Operation)) 
+        {
+            case ('x', '>'):
+                return part.X > condition.Value;
+            case ('x', '<'):
+                return part.X < condition.Value;
+            case ('m', '>'):
+                return part.M > condition.Value;
+            case ('m', '<'):
+                return part.M < condition.Value;
+            case ('a', '>'):
+                return part.A > condition.Value;
+            case ('a', '<'):
+                return part.A < condition.Value;
+            case ('s', '>'):
+                return part.S > condition.Value;
+            case ('s', '<'):
+                return part.S < condition.Value;
+            default:
+                throw new NotImplementedException();
+        }
+    }
+
+    private record Part(int X, int M, int A, int S)
+    { 
+        public int Sum() => X + M + A + S;  
+    }
+
+    private record Rule(Condition Condition, string Result);
+
+    private record Condition(char Property, char Operation, int Value);
+
+    private record Workflow(string Name, Rule[] Rules);
+}