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serenity/Userland/Services/ChessEngine/MCTSTree.h
Peter Elliott 49539abee0 ChessEngine: don't store board in non-leaf nodes in MCTS
Also make parameters static so they aren't in every node of the tree
this saves a substantial amount of memory.
2021-06-22 23:09:42 +02:00

51 lines
1.3 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Function.h>
#include <AK/NonnullOwnPtrVector.h>
#include <AK/OwnPtr.h>
#include <LibChess/Chess.h>
#include <math.h>
class MCTSTree {
public:
enum EvalMethod {
Simulation,
Heuristic,
};
MCTSTree(const Chess::Board& board, MCTSTree* parent = nullptr);
MCTSTree& select_leaf();
MCTSTree& expand();
int simulate_game() const;
int heuristic() const;
void apply_result(int game_score);
void do_round();
Chess::Move best_move() const;
double expected_value() const;
double uct(Chess::Color color) const;
bool expanded() const;
private:
// While static parameters are less configurable, they don't take up any
// memory in the tree, which I believe to be a worthy tradeoff.
static constexpr double s_exploration_parameter { sqrt(2) };
// FIXME: Optimize simulations enough for use.
static constexpr EvalMethod s_eval_method { EvalMethod::Heuristic };
NonnullOwnPtrVector<MCTSTree> m_children;
MCTSTree* m_parent { nullptr };
int m_white_points { 0 };
int m_simulations { 0 };
OwnPtr<Chess::Board> m_board;
Optional<Chess::Move> m_last_move;
Chess::Color m_turn : 2;
bool m_moves_generated : 1 { false };
};