Use ActionSet instead of a List

Simulator/ActionSet.cs

@@ -0,0 +1,69 @@
+using Craftimizer.Simulator.Actions;
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.Intrinsics.X86;
+
+namespace Craftimizer.Simulator;
+
+public record ActionSet
+{
+    public ulong Bits { get; set; }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public bool HasFlag(ActionType action) => (Bits & (1ul << ((int)action + 1))) != 0;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void SetFlag(ActionType action) => Bits |= 1ul << ((int)action + 1);
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public void ClearFlag(ActionType action) => Bits &= ~(1ul << ((int)action + 1));
+
+    public IEnumerable<ActionType> Actions => GetActions();
+
+    private IEnumerable<ActionType> GetActions()
+    {
+        foreach (var action in Enum.GetValues<ActionType>())
+            if (HasFlag(action))
+                yield return action;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static int NthBitSet(ulong value, int n)
+    {
+        if (Bmi2.X64.IsSupported)
+            return BitOperations.TrailingZeroCount(Bmi2.X64.ParallelBitDeposit(1ul << n, value));
+
+        ulong mask = 0x0000FFFFFFFFu;
+        var size = 32;
+        var _base = 0;
+
+        if (n++ >= BitOperations.PopCount(value))
+            return 64;
+
+        while (size > 0)
+        {
+            var count = BitOperations.PopCount(value & mask);
+            if (n > count)
+            {
+                _base += size;
+                size >>= 1;
+                mask |= mask << size;
+            }
+            else
+            {
+                size >>= 1;
+                mask >>= size;
+            }
+        }
+
+        return _base;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public ActionType ActionAt(int index) => (ActionType)(NthBitSet(Bits, index) - 1);
+
+    public int ActionCount => BitOperations.PopCount(Bits);
+
+    public bool IsEmpty => Bits == 0;
+}

Simulator/Simulator.cs

@@ -29,8 +29,6 @@ public class Simulator
     }
     public virtual bool IsComplete => CompletionState != CompletionState.Incomplete;
 
-    public IEnumerable<ActionType> AvailableActions => ActionUtils.AvailableActions(this);
-
 #pragma warning disable CS8618 // Emplace sets all the fields already
     public Simulator(SimulationState state)
 #pragma warning restore CS8618

Solver/Crafty/SimulationNode.cs

@@ -7,10 +7,10 @@ public readonly record struct SimulationNode
 {
     public SimulationState State { get; init; }
     public ActionType? Action { get; init; }
-    public List<ActionType> AvailableActions { get; init; }
+    public ActionSet AvailableActions { get; init; }
     public CompletionState SimulationCompletionState { get; init; }
     public CompletionState CompletionState =>
-        AvailableActions.Count == 0 && SimulationCompletionState == CompletionState.Incomplete ?
+        AvailableActions.IsEmpty && SimulationCompletionState == CompletionState.Incomplete ?
         CompletionState.NoMoreActions :
         SimulationCompletionState;
 

Solver/Crafty/Simulator.cs

@@ -49,14 +49,8 @@ public class Simulator : Sim
         ActionType.BasicTouch,
     };
 
-    // https://github.com/alostsock/crafty/blob/cffbd0cad8bab3cef9f52a3e3d5da4f5e3781842/crafty/src/craft_state.rs#L137
-    public List<ActionType> AvailableActionsHeuristic(bool strict)
-    {
-        if (IsComplete)
-            return new();
-
-        ActionUtils.SetSimulation(this);
-        return AcceptedActions.Where(action =>
+    // https://github.com/alostsock/crafty/blob/cffbd0cad8bab3cef9f52a3e3d5da4f5e3781842/crafty/src/craft_state.rs#L146
+    private bool CanUseAction(ActionType action, bool strict)
     {
         var baseAction = action.WithUnsafe();
 
@@ -152,6 +146,19 @@ public class Simulator : Sim
         }
 
         return true;
-        }).ToList();
+    }
+
+    // https://github.com/alostsock/crafty/blob/cffbd0cad8bab3cef9f52a3e3d5da4f5e3781842/crafty/src/craft_state.rs#L137
+    public ActionSet AvailableActionsHeuristic(bool strict)
+    {
+        if (IsComplete)
+            return new();
+
+        ActionUtils.SetSimulation(this);
+        var ret = new ActionSet();
+        foreach(var action in AcceptedActions)
+            if (CanUseAction(action, strict))
+                ret.SetFlag(action);
+        return ret;
     }
 }

Solver/Crafty/Solver.cs

@@ -56,8 +56,9 @@ public class Solver
             if (node.IsComplete)
                 return (currentIndex, node.CompletionState);
 
-            if (!node.AvailableActions.Remove(action))
+            if (!node.AvailableActions.HasFlag(action))
                 return (currentIndex, CompletionState.InvalidAction);
+            node.AvailableActions.ClearFlag(action);
 
             currentIndex = Tree.Insert(currentIndex, Execute(node.State, action, strict));
         }
@@ -104,7 +105,7 @@ public class Solver
         {
             var selectedNode = Tree.Get(selectedIndex);
 
-            var expandable = selectedNode.State.AvailableActions.Count != 0;
+            var expandable = !selectedNode.State.AvailableActions.IsEmpty;
             var likelyTerminal = selectedNode.Children.Count == 0;
             if (expandable || likelyTerminal) {
                 break;
@@ -123,8 +124,9 @@ public class Solver
         if (initialNode.IsComplete)
             return (initialIndex, initialNode.CompletionState, initialNode.CalculateScore() ?? 0);
 
-        var randomAction = initialNode.AvailableActions.ElementAt(0);
-        initialNode.AvailableActions.RemoveAt(0);
+        var randomIdx = random.Next(initialNode.AvailableActions.ActionCount);
+        var randomAction = initialNode.AvailableActions.ActionAt(randomIdx);
+        initialNode.AvailableActions.ClearFlag(randomAction);
         var expandedState = Execute(initialNode.State, randomAction, true);
         var expandedIndex = Tree.Insert(initialIndex, expandedState);
 
@@ -135,7 +137,8 @@ public class Solver
         {
             if (currentState.IsComplete)
                 break;
-            randomAction = currentState.AvailableActions.ElementAt(0);
+            randomIdx = random.Next(currentState.AvailableActions.ActionCount);
+            randomAction = currentState.AvailableActions.ActionAt(randomIdx);
             currentState = Execute(currentState.State, randomAction, true);
         }