samplesearcher.java

一个黑白棋的源代码(尚未完成

/*
 * SampleSearcher.java
 *
 * Created on 2007-9-29, 14:49:45
 *
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package org.yangcq.logic.search;

import org.yangcq.logic.chessboard.ChessboardImpl;
import org.yangcq.logic.step.Step;

/**
 *
 * @author Administrator
 * 采用最差的极大极小值搜索算法
 */
public class SampleSearcher extends BasicSearcher
{

    private Step bestStep = null;

    public Step getBestStep()
    {
        Step[][] steps = ChessboardImpl.getChessboard().getBoardCopy();
        this.search(steps, ChessboardImpl.getChessboard().getCurrentPlayer().isChessmanBlack(), this.getSearchDepth(), false);
        return this.bestStep;
    }

    protected long search(Step[][] steps, boolean side, long depth, boolean prevPass)//极大极小算法

    {
        long val;
        long current;
        boolean opSide = !side;
        if (depth <= 0)
        {
            return this.getValuer().getValue(steps, side); //估值
        }
        Step[] validStep = this.getStepGenerater().getValidSteps(steps, side); //走法生成
        if (validStep != null)
        {
            val = Long.MIN_VALUE; //初始化为极小值
            for (int i = 0; i < validStep.length; i++)
            {

                long count = this.getStepGenerater().chess(steps, validStep[i].getX(), validStep[i].getY(), validStep[i].getColor().booleanValue()); //走一步
                current = -search(steps, opSide, depth - 1, false); //让对手估值
                this.getStepGenerater().unChess(steps, validStep[i].getX(), validStep[i].getY(), count); //撤销一步
                if (current > val)
                {
                    val = current;
                    if (depth == this.getSearchDepth())
                    {
                        this.bestStep = validStep[i].clone();
                    }
                }
            }
        } else
        {
            if (prevPass)
            {
                val = 0;
                for (int x = 0; x < steps.length; x++)
                {
                    for (int y = 0; y < steps.length; y++)
                    {
                        if (steps[x][y] != null && steps[x][y].getColor().booleanValue() == side)
                        {
                            val++;
                        } else if (steps[x][y] != null && steps[x][y].getColor().booleanValue() == opSide)
                        {
                            val--;
                        }
                    }
                }
            } else
            {
                val = -search(steps, opSide, depth, true);
                if (depth == this.getSearchDepth())
                {
                    this.bestStep = null; //以前可能已经对最好着法赋值，但是那是对手赋的值，所以要擦除
                }
            }
        }

        return val;
    }
}