func negamax(b game.Board, depth, alpha, beta int, color game.Color) (int, game.Move) {
if depth == 0 {
return scoreBoard(b, color), nullMove
}
moves := b.AvailableMoves(color)
if len(moves) == 0 {
return math.MinInt32 + 1, nullMove
}
var (
bestScore = math.MinInt32
bestMove game.Move
)
for _, i := range rand.Perm(len(moves)) {
val, _ := negamax(b.IfMove(moves[i]), depth-1, -beta, -alpha, color.Other())
val = -val
if val > bestScore {
bestScore = val
bestMove = moves[i]
}
if val > alpha {
alpha = val
}
if alpha >= beta {
break
}
}
return bestScore, bestMove
}
func (p httpPlayer) Move(b game.Board) game.Move {
var move game.Move
moveCommand := commandToClient{
Command: "move",
Args: map[string]interface{}{
"board": b,
"moves": b.AvailableMoves(p.Color()),
},
}
if err := p.conn.WriteJSON(moveCommand); err != nil {
log.Printf("error requesting move: %s", err)
return move
}
var resp commandFromClient
if err := p.conn.ReadJSON(&resp); err != nil {
log.Printf("error receiving move: %s", err)
return move
}
if resp.Command != "move" {
log.Printf("expected move command, got: %s", resp.Command)
return move
}
if err := json.Unmarshal(resp.Args, &move); err != nil {
log.Printf("failed unmarshaling move: %s (%s)", resp.Command, string(resp.Args))
return move
}
return move
}
// simple heuristic for board evaluation
func scoreBoard(b game.Board, c game.Color) (score int) {
var myPieceCount, theirPieceCount int
for x := 0; x < b.Width(); x++ {
for y := 0; y < b.Height(); y++ {
sq, _ := b.Get(game.Position{x, y})
if sq.PieceColor == c {
myPieceCount += sq.PieceCount
if sq.PieceCount == 1 || sq.PieceCount > 4 {
score--
}
} else {
theirPieceCount += sq.PieceCount
if sq.PieceCount == 1 || sq.PieceCount > 4 {
score++
}
}
}
}
return score + 5*int(float64(myPieceCount-theirPieceCount)*float64(2*b.Width())/float64(myPieceCount)+0.5)
}
func (p cliPlayer) Move(b game.Board) game.Move {
buf := new(bytes.Buffer)
buf.WriteString(" " + strings.Repeat("-", 5*b.Width()-1) + "\n")
for y := 0; y < b.Height(); y++ {
buf.WriteByte('|')
for x := 0; x < b.Width(); x++ {
sq, _ := b.Get(game.Position{x, y})
if sq.PieceCount == 0 {
buf.WriteString(" ")
} else {
var c string
if sq.PieceColor == game.Black {
c = "b"
} else {
c = "w"
}
num := strconv.Itoa(sq.PieceCount)
if len(num) == 1 {
buf.WriteString(" " + num + c + " ")
} else {
buf.WriteString(num + c + " ")
}
}
buf.WriteByte('|')
}
buf.WriteString(" " + strconv.Itoa(y) + "\n")
buf.WriteString(" " + strings.Repeat("-", 5*b.Width()-1) + "\n")
}
buf.WriteString(" ")
for x := 0; x < b.Width(); x++ {
fmt.Fprintf(buf, " %2d ", x)
}
buf.WriteString("\n\n")
clear := exec.Command("clear")
clear.Stdout = os.Stdout
clear.Run()
os.Stdout.Write(buf.Bytes())
for {
var (
move game.Move
n int
err error
)
for n < 4 || err != nil {
fmt.Fprintf(os.Stdout, "Enter move for %s (fromx,fromy tox,toy count): ", p.Name())
scanner := bufio.NewScanner(os.Stdin)
scanner.Scan()
n, err = fmt.Sscanf(scanner.Text(), "%d,%d %d,%d %d",
&move.From.X,
&move.From.Y,
&move.To.X,
&move.To.Y,
&move.PieceCount,
)
}
available := b.AvailableMoves(p.Color())
for _, m := range available {
if move == m {
return move
}
}
fmt.Fprintf(os.Stdout, "Move %+v is not legal!\n", move)
}
}
func (p randomPlayer) Move(b game.Board) game.Move {
moves := b.AvailableMoves(p.Color())
return moves[rand.Intn(len(moves))]
}