5 releases (3 breaking)
0.4.0 | Jan 14, 2024 |
---|---|
0.3.0 | Mar 7, 2022 |
0.2.1 | Jul 11, 2021 |
0.2.0 | Feb 23, 2021 |
0.1.0 | Jun 27, 2019 |
#7 in #tic-tac-toe
44 downloads per month
Used in pgn-traits
10KB
96 lines
Overview
A collection of minimal traits for abstractly representing 2-player board games. The traits can be implemented for any sequential, deterministic, perfect-information game. This includes many popular games such as chess, go, xiangqi, othello, connect four and tic-tac-toe.
No implementations are provided in this crate.
Usage examples
Count the total number of moves possible at n moves deep. Commonly called a perf test and used to check the correctness of move generation:
pub fn perft<B: Board>(board: &mut B, depth: u16) -> u64 {
if depth == 0 {
1
} else {
let mut moves = vec![];
board.generate_moves(&mut moves);
moves
.into_iter()
.map(|mv| {
let reverse_move = board.do_move(mv);
let num_moves = perft(board, depth - 1);
board.reverse_move(reverse_move);
num_moves
})
.sum()
}
}
The Minimax algorithm, running n plies ahead:
fn minimax<B: EvalBoard>(board: &mut B, depth: u16) -> f32 {
match board.game_result() {
Some(GameResult::WhiteWin) => return 100.0,
Some(GameResult::BlackWin) => return -100.0,
Some(GameResult::Draw) => return 0.0,
None => (),
}
if depth == 0 {
board.static_eval()
} else {
let side_to_move = board.side_to_move();
let mut moves = vec![];
board.generate_moves(&mut moves);
let child_evaluations = moves.into_iter().map(|mv| {
let reverse_move = board.do_move(mv);
let eval = minimax(board, depth - 1);
board.reverse_move(reverse_move);
eval
});
match side_to_move {
Color::White => child_evaluations
.max_by(|a, b| a.partial_cmp(b).unwrap())
.unwrap(),
Color::Black => child_evaluations
.min_by(|a, b| a.partial_cmp(b).unwrap())
.unwrap(),
}
}
}