这是我的minmax算法的代码：
SQL> declare
2 l_heat number;
3 l_stop varchar2(1) := 'N';
4 begin
5 -- simulating temperature readings
6 while l_stop = 'N' loop
7 l_heat := round(dbms_random.value * 7500);
8 p_sense(l_heat, l_stop);
9 end loop;
10 end;
11 /
PL/SQL procedure successfully completed.
SQL> select count(*) from ir_sense;
COUNT(*)
----------
3
SQL> select * from ir_sense;
HEAT
----------
187
2328
1072
移动是一个对象，用于存储从位置，到位置以及与移动后的棋盘值相关联的分数。行private static void minmax(){
Move move = max(4, true, null);
//System.out.println(move);
board.makeMove(move.getFromPoint(), move.getToPoint());
}
private static Move max(int depth, boolean player, Move passedMove){
if(depth == 0) return passedMove.setScore(board.boardVal());
Move max = new Move(Integer.MIN_VALUE);
for(int i = 0; i < board.getMoves(player).size(); i++){
Move move = board.getMoves(player).get(i);
board.makeMove(move.getFromPoint(), move.getToPoint());
//System.out.println(board);
Move scoreMove = min(depth - 1, !player, move);
board.undo();
if(scoreMove.getScore() > max.getScore()) max = new Move(move.getFromPoint(), move.getToPoint(), scoreMove.getScore());
}
return max;
}
private static Move min(int depth, boolean player, Move passedMove){
if(depth == 0) return passedMove.setScore(-board.boardVal());
Move min = new Move(Integer.MAX_VALUE);
for(int i = 0; i < board.getMoves(player).size(); i++){
Move move = board.getMoves(player).get(i);
board.makeMove(move.getFromPoint(), move.getToPoint());
//System.out.println(board);
Move scoreMove = max(depth - 1, !player, move);
board.undo();
if(scoreMove.getScore() < min.getScore()) min = new Move(move.getFromPoint(), move.getToPoint(), scoreMove.getScore());
}
return min;
}
为“移动”分配一个空值（我不明白为什么），并且在运行方法后，它会使棋盘处于一个奇怪的状态，看起来这些动作没有被正确撤消，但是我已经反复检查过这个功能。
以下是运行代码的示例（在注释掉Move move = max(4, true, null);行以防止空指针异常之后）：
board.makeMove(move.getFromPoint(), move.getToPoint());只留下计算机的碎片，移除所有玩家。
移动课程：
8 [R] [N] [B] [Q] [K] [B] [N] [R]
7 [P] [P] [P] [P] [P] [P] [P] [P]
6 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
5 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
4 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
3 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
2 [P] [P] [P] [P] [P] [P] [P] [P]
1 [R] [N] [B] [Q] [K] [B] [N] [R]
a b c d e f g h
a2,a4
8 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
7 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
6 [ ] [ ] [ ] [ ] [ ] [ ] [N] [ ]
5 [ ] [ ] [N] [ ] [ ] [ ] [R] [K]
4 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
3 [ ] [ ] [ ] [ ] [ ] [ ] [B] [B]
2 [ ] [P] [ ] [ ] [ ] [ ] [ ] [ ]
1 [P] [ ] [R] [P] [P] [P] [P] [P]
a b c d e f g h
Board Class建立在一堆2D数组上，这里有移动和撤消方法：
public class Move {
private Point fromPoint;
private Point toPoint;
private int score;
public Move(Point fromPoint, Point toPoint, int score){
this.fromPoint = fromPoint;
this.toPoint = toPoint;
this.score = score;
}
public Move(Point fromPoint, Point toPoint){
this(fromPoint, toPoint, 0);
}
public Move(int score){
this(null, null, score);
}
public Point getFromPoint() {
return fromPoint;
}
public Point getToPoint() {
return toPoint;
}
public int getScore() {
return score;
}
public Move setScore(int score){
this.score = score;
return this;
}
@Override
public String toString(){
return "(" + fromPoint.y + ", " + fromPoint.x + ")" + " (" + toPoint.y + ", " + toPoint.x + ") " + score;
}
}
我希望程序返回一个最佳Move（导致最高得分板状态的那个）并在执行minmax方法之前离开板。这些都没有发生，方法返回null并且电路板完全改变了。
更改Board类中的makeMove（）方法以正确复制板后，我现在在该方法中获得NullPointerExceptions：
public void makeMove(Point fromPoint, Point toPoint){
Piece[][] boardNode = new Piece[board.peek().length][];
for(int i = 0; i < boardNode.length; i++){ //this was changed
boardNode[i] = board.peek()[i].clone();
}
boardNode[fromPoint.y][fromPoint.x].setPoint(toPoint);
boardNode[toPoint.y][toPoint.x] = boardNode[fromPoint.y][fromPoint.x];
boardNode[fromPoint.y][fromPoint.x] = null;
board.push(boardNode);
}
public void undo(){
board.pop();
}
public ArrayList<Move> getMoves(boolean color){
ArrayList<Move> moves = new ArrayList<>();
for(Piece[] row : board.peek()){
for(Piece piece : row){
if(piece != null) {
for (Point point : piece.moves()) {
if (piece.getColor() == color && straightLine(piece.getPoint(), point) && (board.peek()[point.y][point.x] == null || board.peek()[point.y][point.x].getColor() != color)) moves.add(new Move(piece.getPoint(), point));
}
}
}
}
return moves;
}
...
8 [R] [N] [B] [Q] [K] [B] [N] [R]
7 [P] [P] [P] [P] [P] [P] [P] [P]
6 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
5 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
4 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
3 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
2 [P] [P] [P] [P] [P] [P] [P] [P]
1 [R] [N] [B] [Q] [K] [B] [N] [R]
a b c d e f g h
a2,a4
Exception in thread "main" java.lang.NullPointerException
at Board.makeMove(Board.java:45)
at ChessMain.min(ChessMain.java:87)
at ChessMain.max(ChessMain.java:75)
at ChessMain.min(ChessMain.java:89)
at ChessMain.max(ChessMain.java:75)
at ChessMain.minmax(ChessMain.java:63)
at ChessMain.play(ChessMain.java:58)
at ChessMain.main(ChessMain.java:15)
以下是扩展Piece的对象示例：
public abstract class Piece {
private boolean color;
private Point getPoint;
public Piece(int x, int y, boolean color){
this.color = color;
getPoint = new Point(x, y);
}
abstract int getValue();
public String toString(){
return "";
}
public void setPoint(Point point){
this.getPoint = point;
}
public Point getPoint(){ return getPoint; }
public boolean takable(Point point){ return containsPoint(moves(), point); }
private static boolean containsPoint(ArrayList<Point> list, Point point){
for(Point listPoint: list){
if(listPoint.x == point.x && listPoint.y == point.y) return true;
}
return false;
}
abstract ArrayList<Point> moves();
public boolean getColor(){ return color; }
}
如果有更多信息可以帮助我，请告诉我。
感谢任何帮助。
答案 0 :(得分：2)
我可以看到一个问题：
public void makeMove(Point fromPoint, Point toPoint){
Piece[][] boardNode = board.peek(); // WARNING!!!
// Instead, make a copy of the previous board state
// so you don't change all board states when you want to change one.
boardNode[fromPoint.y][fromPoint.x].setPoint(toPoint);
boardNode[toPoint.y][toPoint.x] = boardNode[fromPoint.y][fromPoint.x];
boardNode[fromPoint.y][fromPoint.x] = null;
board.push(boardNode); // WARNING!!!
}
您的board在每个级别的堆栈上使用相同的引用。
当您调用Piece[][] boardNode = board.peek(); ... board.push(boardNode);时，您实际上只是对所有电路板状态使用相同的参考，修改其中一个将修改所有参考的对象..我认为这不是您想要的。< / p>
这可能是您问题的根源，如果除此之外还有更多问题，请更新您的问题。
更新
克隆电路板状态的2D数组仍然是一个问题。您克隆了数组，但没有克隆Piece，因此当您更新该片段的位置时，它正在更新该对象的所有状态参考。
首先，制作片段实施Cloneable
public abstract class Piece implements Cloneable {
// ...
@Override
public abstract Piece clone();
然后让所有孩子Pieces实际克隆自己，例如Pawn执行此操作：
@Override
public Pawn clone() {
return new Pawn(getPoint.x, getPoint.y, color);
}
然后这将克隆您的2D数组：
public void makeMove(Point fromPoint, Point toPoint) {
final Piece[][] prevBoard = board.peek();
final int width = prevBoard.length;
Piece[][] boardNode = new Piece[width][];
for (int i = 0; i < width; i++) {
final int height = prevBoard[i].length;
boardNode[i] = new Piece[height];
for (int j = 0; j < height; j++) {
Piece p = prevBoard[i][j];
if (p == null) {
boardNode[i][j] = null;
} else {
boardNode[i][j] = p.clone();
}
}
}
这似乎让你走上了正确的轨道，但现在看来对手正在移动球员的碎片，或类似的东西。
祝其他人好运！