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https://github.com/RGBCube/serenity
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d5979516b4
Computation from last turn might have produced some nodes that are still accurate. Keeping them should make the engine a bit smarter.
57 lines
1.5 KiB
C++
57 lines
1.5 KiB
C++
/*
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* Copyright (c) 2020, the SerenityOS developers.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Function.h>
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#include <AK/NonnullOwnPtrVector.h>
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#include <AK/OwnPtr.h>
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#include <LibChess/Chess.h>
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#include <math.h>
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class MCTSTree {
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public:
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enum EvalMethod {
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Simulation,
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Heuristic,
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};
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MCTSTree(Chess::Board const& board, MCTSTree* parent = nullptr);
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MCTSTree(MCTSTree&&);
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MCTSTree& select_leaf();
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MCTSTree& expand();
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int simulate_game() const;
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int heuristic() const;
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void apply_result(int game_score);
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void do_round();
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Optional<MCTSTree&> child_with_move(Chess::Move);
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MCTSTree& best_node();
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Chess::Move last_move() const;
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double expected_value() const;
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double uct(Chess::Color color) const;
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bool expanded() const;
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private:
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// While static parameters are less configurable, they don't take up any
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// memory in the tree, which I believe to be a worthy tradeoff.
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static constexpr double s_exploration_parameter { M_SQRT2 };
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static constexpr int s_number_of_visit_parameter { 1 };
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// FIXME: Optimize simulations enough for use.
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static constexpr EvalMethod s_eval_method { EvalMethod::Heuristic };
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NonnullOwnPtrVector<MCTSTree> m_children;
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MCTSTree* m_parent { nullptr };
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int m_white_points { 0 };
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int m_simulations { 0 };
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OwnPtr<Chess::Board> m_board;
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Optional<Chess::Move> m_last_move;
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Chess::Color m_turn : 2;
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bool m_moves_generated : 1 { false };
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};
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