def alphabeta(board, depth, a, b, maximizing):
if (depth == 0):
return Heuristics.evaluate(board)
if (maximizing):
best_score = -AI.INFINITE
for move in board.get_possible_moves(pieces.Piece.WHITE):
copy = board.Board.clone(board)
copy.perform_move(move)
best_score = max(best_score, AI.alphabeta(copy, depth-1, a, b, False))
a = max(a, best_score)
if (b <= a):
break
return best_score
else:
best_score = AI.INFINITE
for move in board.get_possible_moves(pieces.Piece.BLACK):
copy = board.Board.clone(board)
copy.perform_move(move)
best_score = min(best_score, AI.alphabeta(copy, depth-1, a, b, True))
b = min(b, best_score)
if (b <= a):
break
return best_score
def get_ai_move(board, invalid_moves):
best_move = 0
best_score = AI.INFINITE
for move in board.get_possible_moves(pieces.Piece.BLACK):
if (AI.is_invalid_move(move, invalid_moves)):
continue
copy = board.Board.clone(board)
copy.perform_move(move)
score = AI.alphabeta(copy, 3, -AI.INFINITE, AI.INFINITE, True)
if (score < best_score):
best_score = score
best_move = move
# Checkmate.
if (best_move == 0):
return 0
copy = board.Board.clone(board)
copy.perform_move(best_move)
if (copy.is_check(pieces.Piece.BLACK)):
invalid_moves.append(best_move)
return AI.get_ai_move(board, invalid_moves)
return best_move
def minimax(board, depth, maximizing):
if (depth == 0):
return Heuristics.evaluate(board)
if (maximizing):
best_score = -AI.INFINITE
for move in board.get_possible_moves(pieces.Piece.WHITE):
copy = board.Board.clone(board)
copy.perform_move(move)
score = AI.minimax(copy, depth-1, False)
best_score = max(best_score, score)
return best_score
else:
best_score = AI.INFINITE
for move in board.get_possible_moves(pieces.Piece.BLACK):
copy = board.Board.clone(board)
copy.perform_move(move)
score = AI.minimax(copy, depth-1, True)
best_score = min(best_score, score)
return best_score
def get_valid_user_move(board):
while True:
move = get_user_move()
valid = False
possible_moves = board.get_possible_moves(pieces.Piece.WHITE)
# No possible moves
if (not possible_moves):
return 0
for possible_move in possible_moves:
if (move.equals(possible_move)):
move.castling_move = possible_move.castling_move
valid = True
break
if (valid):
break
else:
print("Invalid move.")
return move
def get_valid_user_move(board, api, uid, request):
while True:
move = get_user_move(api, uid, request)
valid = False
possible_moves = board.get_possible_moves(pieces.Piece.WHITE)
# No possible moves
if (not possible_moves):
return 0
for possible_move in possible_moves:
if (move.equals(possible_move)):
move.castling_move = possible_move.castling_move
valid = True
break
if (valid):
break
else:
break
return move
def get_valid_user_move(board, color=pieces.Piece.WHITE):
while True:
move = get_user_move(color)
valid = False
possible_moves = board.get_possible_moves(color)
# No possible moves
if (not possible_moves):
return 0
for possible_move in possible_moves:
if (move.equals(possible_move)):
valid = True
break
if valid:
break
else:
print(move.to_string())
print("Invalid move.")
return move
