Improved solver performance

shenzhen_solitaire/solver/solver.py

@@ -2,52 +2,55 @@
 import typing
 from typing import Iterator, List, Optional
 import time
-
+from dataclasses import dataclass
 from ..board import Board
 from . import board_actions
 from .board_actions import DragonKillAction, GoalAction, HuaKillAction, MoveAction
 from .board_possibilities import possible_actions
 
 
+@dataclass
+class ActionStackFrame:
+    iterator: Iterator[board_actions.Action]
+    action: Optional[board_actions.Action]
+    state: int
+
+    def next(self) -> Optional[board_actions.Action]:
+        """Get next iteration of top action iterator"""
+        try:
+            self.action = next(self.iterator)
+        except StopIteration:
+            return None
+        return self.action
+
+
 class ActionStack:
     """Stack of chosen actions on the board"""
 
-    iterator_stack: List[Iterator[board_actions.Action]]
-    action_stack: List[Optional[board_actions.Action]]
-    index_stack: List[int]
-    state_stack: List[int]
-
     def __init__(self) -> None:
-        self.iterator_stack = []
-        self.index_stack = []
-        self.action_stack = []
-        self.state_stack = []
+        self.frames: List[ActionStackFrame] = []
 
     def push(self, board: Board) -> None:
         """Append another board state to stack"""
-        self.iterator_stack.append(possible_actions(board))
-        self.action_stack.append(None)
-        self.index_stack.append(0)
-        self.state_stack.append(board.state_identifier)
+        self.frames.append(
+            ActionStackFrame(
+                iterator=iter(possible_actions(board)),
+                action=None,
+                state=board.state_identifier,
+            )
+        )
 
-    def get(self) -> Optional[board_actions.Action]:
+    @property
+    def top(self) -> ActionStackFrame:
         """Get next iteration of top action iterator"""
-        try:
-            self.action_stack[-1] = next(self.iterator_stack[-1])
-        except StopIteration:
-            return None
-        self.index_stack[-1] += 1
-        return self.action_stack[-1]
+        return self.frames[-1]
 
     def pop(self) -> None:
         """Pop one action from stack"""
-        self.action_stack.pop()
-        self.iterator_stack.pop()
-        self.index_stack.pop()
-        self.state_stack.pop()
+        self.frames.pop()
 
     def __len__(self) -> int:
-        return len(self.index_stack)
+        return len(self.frames)
 
 
 def solve(
@@ -61,27 +64,30 @@ def solve(
     def _limit_stack_size(stack_size: int) -> None:
         if len(stack) == stack_size:
             stack.pop()
-            assert stack.action_stack[-1] is not None
-            stack.action_stack[-1].undo(board)
+            assert stack.top.action is not None
+            stack.top.action.undo(board)
             assert board.state_identifier in state_set
 
     def _backtrack_action() -> None:
         stack.pop()
-        assert stack.action_stack[-1] is not None
-        stack.action_stack[-1].undo(board)
+        assert stack.top.action is not None
+        stack.top.action.undo(board)
         assert board.state_identifier in state_set
 
     def _skip_loop_move(action: board_actions.Action) -> bool:
-        if isinstance(action, MoveAction):
-            for prev_action in stack.action_stack[-2::-1]:
-                if isinstance(prev_action, MoveAction):
-                    if prev_action.cards == action.cards:
-                        return True
+        if not isinstance(action, MoveAction):
+            return False
+        for frame in stack.frames[-2::-1]:
+            if not isinstance(frame.action, MoveAction):
+                continue
+            if frame.action.cards == action.cards:
+                return True
         return False
 
     iter_start = time.time()
     count = 0
     while stack:
+
         count += 1
         if count > 5000:
             count = 0
@@ -92,10 +98,10 @@ def solve(
 
         # _limit_stack_size(80)
 
-        assert board.state_identifier == stack.state_stack[-1]
-        action = stack.get()
+        assert board.state_identifier == stack.top.state
+        action = stack.top.next()
 
-        if not action:
+        if action is None:
             _backtrack_action()
             continue
 
@@ -105,14 +111,11 @@ def solve(
         action.apply(board)
 
         if board.solved():
-            yield stack.action_stack
+            assert all(x.action is not None for x in stack.frames)
+            yield [typing.cast(board_actions.Action, x.action) for x in stack.frames]
             iter_start = time.time()
-            stack.action_stack[-1].undo(board)
-            while isinstance(
-                stack.action_stack[-1], (GoalAction, HuaKillAction, DragonKillAction)
-            ):
-                stack.pop()
-                stack.action_stack[-1].undo(board)
+            action.undo(board)
+            assert board.state_identifier in state_set
             continue
 
         if board.state_identifier in state_set: