Split solver into MCTS and algorithms

.editorconfig

@@ -158,6 +158,7 @@ dotnet_diagnostic.CA1841.severity = suggestion
 dotnet_diagnostic.CA1845.severity = suggestion
 dotnet_diagnostic.MA0011.severity = silent
 dotnet_diagnostic.MA0076.severity = silent
+dotnet_diagnostic.MA0046.severity = silent
 dotnet_diagnostic.MA0002.severity = silent
 csharp_style_prefer_switch_expression = true:suggestion
 csharp_style_prefer_pattern_matching = true:silent

Benchmark/Program.cs

@@ -77,11 +77,11 @@ internal static class Program
 
         Console.WriteLine($"{state.Quality} {state.CP} {state.Progress} {state.Durability}");
         //return;
-        var (_, s) = Solver.Solver.SearchStepwiseFurcated(config, state, a => Console.WriteLine(a), default);
+        var (_, s) = config.Invoke(state, a => Console.WriteLine(a))!.Value;
         Console.WriteLine($"Qual: {s.Quality}/{s.Input.Recipe.MaxQuality}");
         return;
 
-        Solver.Solver.SearchStepwiseFurcated(config, new(input), null, default);
+        config.Invoke(new(input));
         //Benchmark(() => );
     }
 

Craftimizer/Configuration.cs

@@ -15,25 +15,6 @@ public class Macro
     public List<ActionType> Actions { get; set; } = new();
 }
 
-public static class AlgorithmUtils
-{
-    public static void Invoke(this SolverConfig me, SimulationState state, Action<ActionType>? actionCallback = null, CancellationToken token = default)
-    {
-        try
-        {
-            Solver.Solver.Search(me, state, actionCallback, token);
-        }
-        catch (AggregateException e)
-        {
-            e.Handle(ex => ex is OperationCanceledException);
-        }
-        catch (OperationCanceledException)
-        {
-
-        }
-    }
-}
-
 [Serializable]
 public class Configuration : IPluginConfiguration
 {

Simulator/CompletionState.cs

@@ -6,5 +6,7 @@ public enum CompletionState : byte
     ProgressComplete,
     NoMoreDurability,
 
-    Other
+    InvalidAction,
+    MaxActionCountReached,
+    NoMoreActions
 }

Simulator/Simulator.cs

@@ -21,8 +21,17 @@ public class Simulator
 
     public bool IsFirstStep => State.StepCount == 0;
 
-    public CompletionState CompletionState => CalculateCompletionState(State);
+    public virtual CompletionState CompletionState {
-    public virtual bool IsComplete => CompletionState != CompletionState.Incomplete;
+        get
+        {
+            if (Progress >= Input.Recipe.MaxProgress)
+                return CompletionState.ProgressComplete;
+            if (Durability <= 0)
+                return CompletionState.NoMoreDurability;
+            return CompletionState.Incomplete;
+        }
+    }
+    public bool IsComplete => CompletionState != CompletionState.Incomplete;
 
     public IEnumerable<ActionType> AvailableActions => ActionUtils.AvailableActions(this);
 
@@ -278,13 +287,4 @@ public class Simulator
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void IncreaseQuality(float efficiency) =>
         IncreaseQualityRaw(CalculateQualityGain(efficiency, false));
-
-    public static CompletionState CalculateCompletionState(SimulationState state)
-    {
-        if (state.Progress >= state.Input.Recipe.MaxProgress)
-            return CompletionState.ProgressComplete;
-        if (state.Durability <= 0)
-            return CompletionState.NoMoreDurability;
-        return CompletionState.Incomplete;
-    }
 }

Solver/CompletionState.cs

@@ -1,20 +0,0 @@
-using CompState = Craftimizer.Simulator.CompletionState;
-
-namespace Craftimizer.Solver;
-
-public enum CompletionState : byte
-{
-    Incomplete,
-    ProgressComplete,
-    NoMoreDurability,
-
-    InvalidAction,
-    MaxActionCountReached,
-    NoMoreActions
-}
-
-internal static class CompletionStateUtils
-{
-    public static CompState IntoBase(this CompletionState me) =>
-        (CompState)me >= CompState.Other ? CompState.Other : (CompState)me;
-}

Solver/MCTS.cs

@@ -0,0 +1,338 @@
+using Craftimizer.Simulator.Actions;
+using Craftimizer.Simulator;
+using System.Diagnostics.Contracts;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Text;
+using Node = Craftimizer.Solver.ArenaNode<Craftimizer.Solver.SimulationNode>;
+
+namespace Craftimizer.Solver;
+
+// https://github.com/alostsock/crafty/blob/cffbd0cad8bab3cef9f52a3e3d5da4f5e3781842/crafty/src/simulator.rs
+public sealed class MCTS
+{
+    private readonly MCTSConfig config;
+    private readonly Node rootNode;
+    private readonly RootScores rootScores;
+
+    public float MaxScore => rootScores.MaxScore;
+
+    public MCTS(MCTSConfig config, SimulationState state)
+    {
+        this.config = config;
+        var sim = new Simulator(state, config.MaxStepCount);
+        rootNode = new(new(
+            state,
+            null,
+            sim.CompletionState,
+            sim.AvailableActionsHeuristic(config.StrictActions)
+        ));
+        rootScores = new();
+    }
+
+    private static SimulationNode Execute(Simulator simulator, SimulationState state, ActionType action, bool strict)
+    {
+        (_, var newState) = simulator.Execute(state, action);
+        return new(
+            newState,
+            action,
+            simulator.CompletionState,
+            simulator.AvailableActionsHeuristic(strict)
+        );
+    }
+
+    private static Node ExecuteActions(Simulator simulator, Node startNode, ReadOnlySpan<ActionType> actions, bool strict)
+    {
+        foreach (var action in actions)
+        {
+            var state = startNode.State;
+            if (state.IsComplete)
+                return startNode;
+
+            if (!state.AvailableActions.HasAction(action))
+                return startNode;
+            state.AvailableActions.RemoveAction(action);
+
+            startNode = startNode.Add(Execute(simulator, state.State, action, strict));
+        }
+
+        return startNode;
+    }
+
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static (int arrayIdx, int subIdx) ChildMaxScore(ref NodeScoresBuffer scores)
+    {
+        var length = scores.Count;
+        var vecLength = Vector<float>.Count;
+
+        var max = (0, 0);
+        var maxScore = 0f;
+        for (var i = 0; length > 0; ++i)
+        {
+            var iterCount = Math.Min(vecLength, length);
+
+            ref var chunk = ref scores.Data[i];
+            var m = new Vector<float>(chunk.MaxScore.Span);
+
+            var idx = Intrinsics.HMaxIndex(m, iterCount);
+
+            if (m[idx] >= maxScore)
+            {
+                max = (i, idx);
+                maxScore = m[idx];
+            }
+
+            length -= iterCount;
+        }
+
+        return max;
+    }
+
+    // Calculates the best child node to explore next
+    // Exploitation: ((1 - w) * (s / v)) + (w * m)
+    // Exploration: sqrt(c * ln(V) / v)
+    // w = maxScoreWeightingConstant
+    // s = score sum
+    // m = max score
+    // v = visits
+    // V = parentVisits
+    // c = explorationConstant
+
+    // Somewhat based off of https://en.wikipedia.org/wiki/Monte_Carlo_tree_search#Exploration_and_exploitation
+    // Here, w_i = (1-w)*score sum
+    // n_i = visits
+    // max score is tacked onto it
+    // N_i = parent visits
+    // c = exploration constant (but crafty places it inside the sqrt..?)
+    [Pure]
+    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
+    private static (int arrayIdx, int subIdx) EvalBestChild(
+        float explorationConstant,
+        float maxScoreWeightingConstant,
+        int parentVisits,
+        ref NodeScoresBuffer scores)
+    {
+        var length = scores.Count;
+        var vecLength = Vector<float>.Count;
+
+        var C = MathF.Sqrt(explorationConstant * MathF.Log(parentVisits));
+        var w = maxScoreWeightingConstant;
+        var W = 1f - w;
+        var CVector = new Vector<float>(C);
+
+        var max = (0, 0);
+        var maxScore = 0f;
+        for (var i = 0; length > 0; ++i)
+        {
+            var iterCount = Math.Min(vecLength, length);
+
+            ref var chunk = ref scores.Data[i];
+            var s = new Vector<float>(chunk.ScoreSum.Span);
+            var vInt = new Vector<int>(chunk.Visits.Span);
+            var m = new Vector<float>(chunk.MaxScore.Span);
+
+            vInt = Vector.Max(vInt, Vector<int>.One);
+            var v = Vector.ConvertToSingle(vInt);
+
+            var exploitation = W * (s / v) + w * m;
+            var exploration = CVector * Intrinsics.ReciprocalSqrt(v);
+            var evalScores = exploitation + exploration;
+
+            var idx = Intrinsics.HMaxIndex(evalScores, iterCount);
+
+            if (evalScores[idx] >= maxScore)
+            {
+                max = (i, idx);
+                maxScore = evalScores[idx];
+            }
+
+            length -= iterCount;
+        }
+
+        return max;
+    }
+
+    [Pure]
+    private Node Select()
+    {
+        var node = rootNode;
+        var nodeVisits = rootScores.Visits;
+
+        float explorationConstant = config.ExplorationConstant, maxScoreWeightingConstant = config.MaxScoreWeightingConstant;
+        while (true)
+        {
+            var expandable = !node.State.AvailableActions.IsEmpty;
+            var likelyTerminal = node.Children.Count == 0;
+            if (expandable || likelyTerminal)
+                return node;
+
+            // select the node with the highest score
+            var at = EvalBestChild(explorationConstant, maxScoreWeightingConstant, nodeVisits, ref node.ChildScores);
+            nodeVisits = node.ChildScores.GetVisits(at);
+            node = node.ChildAt(at)!;
+        }
+    }
+
+    private (Node ExpandedNode, float Score) ExpandAndRollout(Random random, Simulator simulator, Node initialNode)
+    {
+        ref var initialState = ref initialNode.State;
+        // expand once
+        if (initialState.IsComplete)
+            return (initialNode, initialState.CalculateScore(config) ?? 0);
+
+        var poppedAction = initialState.AvailableActions.PopRandom(random);
+        var expandedNode = initialNode.Add(Execute(simulator, initialState.State, poppedAction, true));
+
+        // playout to a terminal state
+        var currentState = expandedNode.State.State;
+        var currentCompletionState = expandedNode.State.SimulationCompletionState;
+        var currentActions = expandedNode.State.AvailableActions;
+
+
+        byte actionCount = 0;
+        Span<ActionType> actions = stackalloc ActionType[Math.Min(config.MaxStepCount - currentState.ActionCount, config.MaxRolloutStepCount)];
+        while (SimulationNode.GetCompletionState(currentCompletionState, currentActions) == CompletionState.Incomplete &&
+            actionCount < actions.Length)
+        {
+            var nextAction = currentActions.SelectRandom(random);
+            actions[actionCount++] = nextAction;
+            (_, currentState) = simulator.Execute(currentState, nextAction);
+            currentCompletionState = simulator.CompletionState;
+            if (currentCompletionState != CompletionState.Incomplete)
+                break;
+            currentActions = simulator.AvailableActionsHeuristic(true);
+        }
+
+        // store the result if a max score was reached
+        var score = SimulationNode.CalculateScoreForState(currentState, currentCompletionState, config) ?? 0;
+        if (currentCompletionState == CompletionState.ProgressComplete)
+        {
+            if (score >= config.ScoreStorageThreshold && score >= MaxScore)
+            {
+                var terminalNode = ExecuteActions(simulator, expandedNode, actions[..actionCount], true);
+                return (terminalNode, score);
+            }
+        }
+        return (expandedNode, score);
+    }
+
+    private void Backpropagate(Node startNode, float score)
+    {
+        while (true)
+        {
+            if (startNode == rootNode)
+            {
+                rootScores.Visit(score);
+                break;
+            }
+            startNode.ParentScores!.Value.Visit(startNode.ChildIdx, score);
+
+            startNode = startNode.Parent!;
+        }
+    }
+
+    private void ShowAllNodes()
+    {
+        static void ShowNodes(StringBuilder b, Node node, Stack<Node> path)
+        {
+            path.Push(node);
+            b.AppendLine($"{new string(' ', path.Count)}{node.State.Action}");
+            {
+                for (var i = 0; i < node.Children.Count; ++i)
+                {
+                    var n = node.ChildAt((i >> 3, i & 7))!;
+                    ShowNodes(b, n, path);
+                }
+                path.Pop();
+            }
+        }
+        var b = new StringBuilder();
+        ShowNodes(b, rootNode, new());
+        Console.WriteLine(b.ToString());
+    }
+
+    private bool AllNodesComplete()
+    {
+        static bool NodesIncomplete(Node node, Stack<Node> path)
+        {
+            path.Push(node);
+            if (node.Children.Count == 0)
+            {
+                if (!node.State.AvailableActions.IsEmpty)
+                    return true;
+            }
+            else
+            {
+                for (var i = 0; i < node.Children.Count; ++i)
+                {
+                    var n = node.ChildAt((i >> 3, i & 7))!;
+                    if (NodesIncomplete(n, path))
+                        return true;
+                }
+                path.Pop();
+            }
+            return false;
+        }
+        return !NodesIncomplete(rootNode, new());
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void Search(int iterations, CancellationToken token)
+    {
+        Simulator simulator = new(rootNode.State.State, config.MaxStepCount);
+        var random = rootNode.State.State.Input.Random;
+        var n = 0;
+        for (var i = 0; i < iterations || MaxScore == 0; i++)
+        {
+            if (token.IsCancellationRequested)
+                break;
+
+            var selectedNode = Select();
+            var (endNode, score) = ExpandAndRollout(random, simulator, selectedNode);
+            if (MaxScore == 0)
+            {
+                if (endNode == selectedNode)
+                {
+                    if (n++ > 5000)
+                    {
+                        n = 0;
+                        if (AllNodesComplete())
+                        {
+                            //Console.WriteLine("All nodes solved for. Can't find a valid solution.");
+                            //ShowAllNodes();
+                            return;
+                        }
+                    }
+                }
+                else
+                    n = 0;
+            }
+
+            Backpropagate(endNode, score);
+        }
+    }
+
+    [Pure]
+    public SolverSolution Solution()
+    {
+        var actions = new List<ActionType>();
+        var node = rootNode;
+
+        while (node.Children.Count != 0)
+        {
+            node = node.ChildAt(ChildMaxScore(ref node.ChildScores))!;
+
+            if (node.State.Action != null)
+                actions.Add(node.State.Action.Value);
+        }
+
+        //var at = node.ChildIdx;
+        //ref var sum = ref node.ParentScores!.Value.Data[at.arrayIdx].ScoreSum.Span[at.subIdx];
+        //ref var max = ref node.ParentScores!.Value.Data[at.arrayIdx].MaxScore.Span[at.subIdx];
+        //ref var visits = ref node.ParentScores!.Value.Data[at.arrayIdx].Visits.Span[at.subIdx];
+        //Console.WriteLine($"{sum} {max} {visits}");
+
+        return new(actions, node.State.State);
+    }
+}

Solver/MCTSConfig.cs

@@ -0,0 +1,38 @@
+using System.Runtime.InteropServices;
+
+namespace Craftimizer.Solver;
+
+[StructLayout(LayoutKind.Auto)]
+public readonly record struct MCTSConfig
+{
+    public int MaxStepCount { get; init; }
+    public int MaxRolloutStepCount { get; init; }
+    public bool StrictActions { get; init; }
+
+    public float MaxScoreWeightingConstant { get; init; }
+    public float ExplorationConstant { get; init; }
+    public float ScoreStorageThreshold { get; init; }
+
+    public float ScoreProgress { get; init; }
+    public float ScoreQuality { get; init; }
+    public float ScoreDurability { get; init; }
+    public float ScoreCP { get; init; }
+    public float ScoreSteps { get; init; }
+
+    public MCTSConfig(SolverConfig config)
+    {
+        MaxStepCount= config.MaxStepCount;
+        MaxRolloutStepCount = config.MaxRolloutStepCount;
+        StrictActions = config.StrictActions;
+
+        MaxScoreWeightingConstant = config.MaxScoreWeightingConstant;
+        ExplorationConstant = config.ExplorationConstant;
+        ScoreStorageThreshold = config.ScoreStorageThreshold;
+
+        ScoreProgress = config.ScoreProgressBonus;
+        ScoreQuality = config.ScoreQualityBonus;
+        ScoreDurability = config.ScoreDurabilityBonus;
+        ScoreCP = config.ScoreCPBonus;
+        ScoreSteps = config.ScoreFewerStepsBonus;
+    }
+}

Solver/SimulationNode.cs

@@ -30,7 +30,7 @@ public struct SimulationNode
         CompletionState.NoMoreActions :
         simCompletionState;
 
-    public readonly float? CalculateScore(SolverConfig config) =>
+    public readonly float? CalculateScore(MCTSConfig config) =>
         CalculateScoreForState(State, SimulationCompletionState, config);
 
     private static bool CanByregot(SimulationState state)
@@ -41,7 +41,7 @@ public struct SimulationNode
         return BaseComboAction.VerifyDurability2(state, 10);
     }
 
-    public static float? CalculateScoreForState(SimulationState state, CompletionState completionState, SolverConfig config)
+    public static float? CalculateScoreForState(SimulationState state, CompletionState completionState, MCTSConfig config)
     {
         if (completionState != CompletionState.ProgressComplete)
             return null;
@@ -50,32 +50,32 @@ public struct SimulationNode
             bonus * Math.Min(1f, value / target);
 
         var progressScore = Apply(
-            config.ScoreProgressBonus,
+            config.ScoreProgress,
             state.Progress,
             state.Input.Recipe.MaxProgress
         );
 
         var byregotBonus = CanByregot(state) ? (state.ActiveEffects.InnerQuiet * .2f + 1) * state.Input.BaseQualityGain : 0;
         var qualityScore = Apply(
-            config.ScoreQualityBonus,
+            config.ScoreQuality,
             state.Quality + byregotBonus,
             state.Input.Recipe.MaxQuality
         );
 
         var durabilityScore = Apply(
-            config.ScoreDurabilityBonus,
+            config.ScoreDurability,
             state.Durability,
             state.Input.Recipe.MaxDurability
         );
 
         var cpScore = Apply(
-            config.ScoreCPBonus,
+            config.ScoreCP,
             state.CP,
             state.Input.Stats.CP
         );
 
         var fewerStepsScore =
-            config.ScoreFewerStepsBonus * (1f - (float)(state.ActionCount + 1) / config.MaxStepCount);
+            config.ScoreSteps * (1f - (float)(state.ActionCount + 1) / config.MaxStepCount);
 
         return progressScore + qualityScore + durabilityScore + cpScore + fewerStepsScore;
     }

Solver/Simulator.cs

@@ -9,8 +9,16 @@ public sealed class Simulator : SimulatorNoRandom
 {
     private readonly int maxStepCount;
 
-    public new CompletionState CompletionState => CalculateCompletionState(State, maxStepCount);
+    public override CompletionState CompletionState
-    public override bool IsComplete => CompletionState != CompletionState.Incomplete;
+    {
+        get
+        {
+            var b = base.CompletionState;
+            if (b == CompletionState.Incomplete && (ActionCount + 1) >= maxStepCount)
+                return CompletionState.MaxActionCountReached;
+            return b;
+        }
+    }
 
     public Simulator(SimulationState state, int maxStepCount) : base(state)
     {
@@ -187,8 +195,4 @@ public sealed class Simulator : SimulatorNoRandom
         return ret;
     }
 
-    public static CompletionState CalculateCompletionState(SimulationState state, int maxStepCount) =>
-        state.ActionCount + 1 >= maxStepCount ?
-        CompletionState.MaxActionCountReached :
-        (CompletionState)CalculateCompletionState(state);
 }

Solver/Solver.cs

@@ -1,338 +1,12 @@
 using Craftimizer.Simulator;
 using Craftimizer.Simulator.Actions;
 using System.Diagnostics;
-using System.Diagnostics.Contracts;
-using System.Numerics;
-using System.Runtime.CompilerServices;
-using System.Text;
-using Node = Craftimizer.Solver.ArenaNode<Craftimizer.Solver.SimulationNode>;
 
 namespace Craftimizer.Solver;
 
-// https://github.com/alostsock/crafty/blob/cffbd0cad8bab3cef9f52a3e3d5da4f5e3781842/crafty/src/simulator.rs
+public static class Solver
-public sealed class Solver
 {
-    private SolverConfig config;
+    private static SolverSolution SearchStepwiseFurcated(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
-    private Node rootNode;
-    private RootScores rootScores;
-
-    public float MaxScore => rootScores.MaxScore;
-
-    public Solver(SolverConfig config, SimulationState state)
-    {
-        this.config = config;
-        var sim = new Simulator(state, config.MaxStepCount);
-        rootNode = new(new(
-            state,
-            null,
-            sim.CompletionState,
-            sim.AvailableActionsHeuristic(config.StrictActions)
-        ));
-        rootScores = new();
-    }
-
-    private static SimulationNode Execute(Simulator simulator, SimulationState state, ActionType action, bool strict)
-    {
-        (_, var newState) = simulator.Execute(state, action);
-        return new(
-            newState,
-            action,
-            simulator.CompletionState,
-            simulator.AvailableActionsHeuristic(strict)
-        );
-    }
-
-    private static Node ExecuteActions(Simulator simulator, Node startNode, ReadOnlySpan<ActionType> actions, bool strict)
-    {
-        foreach (var action in actions)
-        {
-            var state = startNode.State;
-            if (state.IsComplete)
-                return startNode;
-
-            if (!state.AvailableActions.HasAction(action))
-                return startNode;
-            state.AvailableActions.RemoveAction(action);
-
-            startNode = startNode.Add(Execute(simulator, state.State, action, strict));
-        }
-
-        return startNode;
-    }
-
-    [Pure]
-    private SolverSolution Solution()
-    {
-        var actions = new List<ActionType>();
-        var node = rootNode;
-
-        while (node.Children.Count != 0)
-        {
-            node = node.ChildAt(ChildMaxScore(ref node.ChildScores))!;
-
-            if (node.State.Action != null)
-                actions.Add(node.State.Action.Value);
-        }
-
-        //var at = node.ChildIdx;
-        //ref var sum = ref node.ParentScores!.Value.Data[at.arrayIdx].ScoreSum.Span[at.subIdx];
-        //ref var max = ref node.ParentScores!.Value.Data[at.arrayIdx].MaxScore.Span[at.subIdx];
-        //ref var visits = ref node.ParentScores!.Value.Data[at.arrayIdx].Visits.Span[at.subIdx];
-        //Console.WriteLine($"{sum} {max} {visits}");
-
-        return new(actions, node.State.State);
-    }
-
-    [Pure]
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static (int arrayIdx, int subIdx) ChildMaxScore(ref NodeScoresBuffer scores)
-    {
-        var length = scores.Count;
-        var vecLength = Vector<float>.Count;
-
-        var max = (0, 0);
-        var maxScore = 0f;
-        for (var i = 0; length > 0; ++i)
-        {
-            var iterCount = Math.Min(vecLength, length);
-
-            ref var chunk = ref scores.Data[i];
-            var m = new Vector<float>(chunk.MaxScore.Span);
-
-            var idx = Intrinsics.HMaxIndex(m, iterCount);
-
-            if (m[idx] >= maxScore)
-            {
-                max = (i, idx);
-                maxScore = m[idx];
-            }
-
-            length -= iterCount;
-        }
-
-        return max;
-    }
-
-    // Calculates the best child node to explore next
-    // Exploitation: ((1 - w) * (s / v)) + (w * m)
-    // Exploration: sqrt(c * ln(V) / v)
-    // w = maxScoreWeightingConstant
-    // s = score sum
-    // m = max score
-    // v = visits
-    // V = parentVisits
-    // c = explorationConstant
-
-    // Somewhat based off of https://en.wikipedia.org/wiki/Monte_Carlo_tree_search#Exploration_and_exploitation
-    // Here, w_i = (1-w)*score sum
-    // n_i = visits
-    // max score is tacked onto it
-    // N_i = parent visits
-    // c = exploration constant (but crafty places it inside the sqrt..?)
-    [Pure]
-    [MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-    private (int arrayIdx, int subIdx) EvalBestChild(int parentVisits, ref NodeScoresBuffer scores)
-    {
-        var length = scores.Count;
-        var vecLength = Vector<float>.Count;
-
-        var C = MathF.Sqrt(config.ExplorationConstant * MathF.Log(parentVisits));
-        var w = config.MaxScoreWeightingConstant;
-        var W = 1f - w;
-        var CVector = new Vector<float>(C);
-
-        var max = (0, 0);
-        var maxScore = 0f;
-        for (var i = 0; length > 0; ++i)
-        {
-            var iterCount = Math.Min(vecLength, length);
-
-            ref var chunk = ref scores.Data[i];
-            var s = new Vector<float>(chunk.ScoreSum.Span);
-            var vInt = new Vector<int>(chunk.Visits.Span);
-            var m = new Vector<float>(chunk.MaxScore.Span);
-
-            vInt = Vector.Max(vInt, Vector<int>.One);
-            var v = Vector.ConvertToSingle(vInt);
-
-            var exploitation = W * (s / v) + w * m;
-            var exploration = CVector * Intrinsics.ReciprocalSqrt(v);
-            var evalScores = exploitation + exploration;
-
-            var idx = Intrinsics.HMaxIndex(evalScores, iterCount);
-
-            if (evalScores[idx] >= maxScore)
-            {
-                max = (i, idx);
-                maxScore = evalScores[idx];
-            }
-
-            length -= iterCount;
-        }
-
-        return max;
-    }
-
-    [Pure]
-    public Node Select()
-    {
-        var node = rootNode;
-        var nodeVisits = rootScores.Visits;
-
-        while (true)
-        {
-            var expandable = !node.State.AvailableActions.IsEmpty;
-            var likelyTerminal = node.Children.Count == 0;
-            if (expandable || likelyTerminal)
-                return node;
-
-            // select the node with the highest score
-            var at = EvalBestChild(nodeVisits, ref node.ChildScores);
-            nodeVisits = node.ChildScores.GetVisits(at);
-            node = node.ChildAt(at)!;
-        }
-    }
-
-    public (Node ExpandedNode, float Score) ExpandAndRollout(Random random, Simulator simulator, Node initialNode)
-    {
-        ref var initialState = ref initialNode.State;
-        // expand once
-        if (initialState.IsComplete)
-            return (initialNode, initialState.CalculateScore(config) ?? 0);
-
-        var poppedAction = initialState.AvailableActions.PopRandom(random);
-        var expandedNode = initialNode.Add(Execute(simulator, initialState.State, poppedAction, true));
-
-        // playout to a terminal state
-        var currentState = expandedNode.State.State;
-        var currentCompletionState = expandedNode.State.SimulationCompletionState;
-        var currentActions = expandedNode.State.AvailableActions;
-
-
-        byte actionCount = 0;
-        Span<ActionType> actions = stackalloc ActionType[Math.Min(config.MaxStepCount - currentState.ActionCount, config.MaxRolloutStepCount)];
-        while (SimulationNode.GetCompletionState(currentCompletionState, currentActions) == CompletionState.Incomplete &&
-            actionCount < actions.Length)
-        {
-            var nextAction = currentActions.SelectRandom(random);
-            actions[actionCount++] = nextAction;
-            (_, currentState) = simulator.Execute(currentState, nextAction);
-            currentCompletionState = simulator.CompletionState;
-            if (currentCompletionState != CompletionState.Incomplete)
-                break;
-            currentActions = simulator.AvailableActionsHeuristic(true);
-        }
-
-        // store the result if a max score was reached
-        var score = SimulationNode.CalculateScoreForState(currentState, currentCompletionState, config) ?? 0;
-        if (currentCompletionState == CompletionState.ProgressComplete)
-        {
-            if (score >= config.ScoreStorageThreshold && score >= MaxScore)
-            {
-                var terminalNode = ExecuteActions(simulator, expandedNode, actions[..actionCount], true);
-                return (terminalNode, score);
-            }
-        }
-        return (expandedNode, score);
-    }
-
-    public void Backpropagate(Node startNode, float score)
-    {
-        while (true)
-        {
-            if (startNode == rootNode)
-            {
-                rootScores.Visit(score);
-                break;
-            }
-            startNode.ParentScores!.Value.Visit(startNode.ChildIdx, score);
-
-            startNode = startNode.Parent!;
-        }
-    }
-
-    private void ShowAllNodes()
-    {
-        static void ShowNodes(StringBuilder b, Node node, Stack<Node> path)
-        {
-            path.Push(node);
-            b.AppendLine($"{new string(' ', path.Count)}{node.State.Action}");
-            {
-                for (var i = 0; i < node.Children.Count; ++i)
-                {
-                    var n = node.ChildAt((i >> 3, i & 7))!;
-                    ShowNodes(b, n, path);
-                }
-                path.Pop();
-            }
-        }
-        var b = new StringBuilder();
-        ShowNodes(b, rootNode, new());
-        Console.WriteLine(b.ToString());
-    }
-
-    private bool AllNodesComplete()
-    {
-        static bool NodesIncomplete(Node node, Stack<Node> path)
-        {
-            path.Push(node);
-            if (node.Children.Count == 0)
-            {
-                if (!node.State.AvailableActions.IsEmpty)
-                    return true;
-            }
-            else
-            {
-                for (var i = 0; i < node.Children.Count; ++i)
-                {
-                    var n = node.ChildAt((i >> 3, i & 7))!;
-                    if (NodesIncomplete(n, path))
-                        return true;
-                }
-                path.Pop();
-            }
-            return false;
-        }
-        return !NodesIncomplete(rootNode, new());
-    }
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private void Search(int iterations, CancellationToken token)
-    {
-        Simulator simulator = new(rootNode.State.State, config.MaxStepCount);
-        var random = rootNode.State.State.Input.Random;
-        var n = 0;
-        for (var i = 0; i < iterations || MaxScore == 0; i++)
-        {
-            if (token.IsCancellationRequested)
-                break;
-
-            var selectedNode = Select();
-            var (endNode, score) = ExpandAndRollout(random, simulator, selectedNode);
-            if (MaxScore == 0)
-            {
-                if (endNode == selectedNode)
-                {
-                    if (n++ > 5000)
-                    {
-                        n = 0;
-                        if (AllNodesComplete())
-                        {
-                            //Console.WriteLine("All nodes solved for. Can't find a valid solution.");
-                            //ShowAllNodes();
-                            return;
-                        }
-                    }
-                }
-                else
-                    n = 0;
-            }
-
-            Backpropagate(endNode, score);
-        }
-    }
-
-    public static SolverSolution SearchStepwiseFurcated(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
     {
         var definiteActionCount = 0;
         var bestSims = new List<(float Score, SolverSolution Result)>();
@@ -354,7 +28,7 @@ public sealed class Solver
                 var st = activeStates[stateIdx];
                 tasks[i] = Task.Run(() =>
                     {
-                        var solver = new Solver(config, activeStates[stateIdx].State);
+                        var solver = new MCTS(new(config), activeStates[stateIdx].State);
                         solver.Search(config.Iterations / config.ForkCount, token);
                         return (solver.MaxScore, stateIdx, solver.Solution());
                     }, token);
@@ -442,7 +116,7 @@ public sealed class Solver
         return result;
     }
 
-    public static SolverSolution SearchStepwiseForked(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
+    private static SolverSolution SearchStepwiseForked(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
     {
         var actions = new List<ActionType>();
         var sim = new Simulator(state, config.MaxStepCount);
@@ -460,7 +134,7 @@ public sealed class Solver
             for (var i = 0; i < config.ForkCount; ++i)
                 tasks[i] = Task.Run(() =>
                 {
-                    var solver = new Solver(config, state);
+                    var solver = new MCTS(new(config), state);
                     solver.Search(config.Iterations / config.ForkCount, token);
                     return (solver.MaxScore, solver.Solution());
                 }, token);
@@ -489,7 +163,7 @@ public sealed class Solver
         return new(actions, state);
     }
 
-    public static SolverSolution SearchStepwise(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
+    private static SolverSolution SearchStepwise(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
     {
         var actions = new List<ActionType>();
         var sim = new Simulator(state, config.MaxStepCount);
@@ -501,7 +175,7 @@ public sealed class Solver
             if (sim.IsComplete)
                 break;
 
-            var solver = new Solver(config, state);
+            var solver = new MCTS(new(config), state);
 
             var s = Stopwatch.StartNew();
             solver.Search(config.Iterations, token);
@@ -526,13 +200,13 @@ public sealed class Solver
         return new(actions, state);
     }
 
-    public static SolverSolution SearchOneshotForked(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
+    private static SolverSolution SearchOneshotForked(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
     {
         var tasks = new Task<(float MaxScore, SolverSolution Solution)>[config.ForkCount];
         for (var i = 0; i < config.ForkCount; ++i)
             tasks[i] = Task.Run(() =>
             {
-                var solver = new Solver(config, state);
+                var solver = new MCTS(new(config), state);
                 solver.Search(config.Iterations / config.ForkCount, token);
                 return (solver.MaxScore, solver.Solution());
             }, token);
@@ -545,9 +219,9 @@ public sealed class Solver
         return solution;
     }
 
-    public static SolverSolution SearchOneshot(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
+    private static SolverSolution SearchOneshot(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
     {
-        var solver = new Solver(config, state);
+        var solver = new MCTS(new(config), state);
         solver.Search(config.Iterations, token);
         var solution = solver.Solution();
         foreach (var action in solution.Actions)
@@ -556,7 +230,7 @@ public sealed class Solver
         return solution;
     }
 
-    public static SolverSolution Search(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback = null, CancellationToken token = default)
+    public static SolverSolution Search(SolverConfig config, SimulationState state, Action<ActionType>? actionCallback, CancellationToken token)
     {
         Func<SolverConfig, SimulationState, Action<ActionType>?, CancellationToken, SolverSolution> func = config.Algorithm switch
         {
@@ -564,7 +238,8 @@ public sealed class Solver
             SolverAlgorithm.OneshotForked => SearchOneshotForked,
             SolverAlgorithm.Stepwise => SearchStepwise,
             SolverAlgorithm.StepwiseForked => SearchStepwiseForked,
-            SolverAlgorithm.StepwiseFurcated or _ => SearchStepwiseFurcated,
+            SolverAlgorithm.StepwiseFurcated => SearchStepwiseFurcated,
+            _ => throw new ArgumentOutOfRangeException(nameof(config), config, $"Invalid algorithm: {config.Algorithm}")
         };
         return func(config, state, actionCallback, token);
     }

Solver/SolverConfig.cs

@@ -1,3 +1,5 @@
+using Craftimizer.Simulator.Actions;
+using Craftimizer.Simulator;
 using System.Runtime.InteropServices;
 
 namespace Craftimizer.Solver;
@@ -65,4 +67,21 @@ public readonly record struct SolverConfig
         FurcatedActionCount = Environment.ProcessorCount / 2,
         Algorithm = SolverAlgorithm.StepwiseForked
     };
+
+    public SolverSolution? Invoke(SimulationState state, Action<ActionType>? actionCallback = null, CancellationToken token = default)
+    {
+        try
+        {
+            return Solver.Search(this, state, actionCallback, token);
+        }
+        catch (AggregateException e)
+        {
+            e.Handle(ex => ex is OperationCanceledException);
+        }
+        catch (OperationCanceledException)
+        {
+
+        }
+        return null;
+    }
 }