diff options
Diffstat (limited to 'src/board/engine.rs')
| -rw-r--r-- | src/board/engine.rs | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/src/board/engine.rs b/src/board/engine.rs index 9b0e36c..ff071ea 100644 --- a/src/board/engine.rs +++ b/src/board/engine.rs @@ -99,11 +99,11 @@ impl Board { eval } - pub fn negamax_search(&mut self, mut alpha: f32, beta: f32, depth_left: u8) -> f32 { - let color = Color::from(self.ply as u8 % 2); - + pub fn negamax_search(&mut self, mut alpha: f32, beta: f32, depth_left: u8) -> (f32, Vec<Move>) { + let mut principal_variation = Vec::new(); + let color = self.color(); if depth_left == 0 { - return self.material_advantage(); + return (self.material_advantage(), principal_variation); } let moves = self.generate_pseudolegal_moves(color); @@ -113,20 +113,24 @@ impl Board { let captured_piece = self.make_move(mov); if !self.is_king_in_check(color) { - let evaluation = -self.negamax_search(-beta, -alpha, depth_left - 1); + let (mut evaluation, mut subtree_pv) = self.negamax_search(-beta, -alpha, depth_left - 1); + evaluation *= -1.; self.unmake_move(mov, captured_piece, ep_target_before, castling_rights_before); if evaluation >= beta { - return beta; // Fail-hard beta-cutoff + return (beta, principal_variation); // Fail-hard beta-cutoff } if evaluation > alpha { - alpha = evaluation + alpha = evaluation; + principal_variation = Vec::with_capacity(depth_left as usize); + principal_variation.push(mov); + principal_variation.append(&mut subtree_pv); } } else { self.unmake_move(mov, captured_piece, ep_target_before, castling_rights_before); } } - alpha + (alpha, principal_variation) } } @@ -166,8 +170,9 @@ mod tests { let fen = String::from("r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - "); let mut board = Board::from_FEN(fen); - let eval = board.negamax_search(-INFINITY, INFINITY, 4); - println!("{}", eval); + let (eval, pv) = board.negamax_search(-INFINITY, INFINITY, 4); + assert_eq!(eval, 0.0); + assert_eq!(pv.len(), 4); } #[test] |