八皇后问题

package qinglin.learn.arithmetic;

public class EightQueens_03
{
	String position[][]=new String[8][8];
	int column[] = new int[8];
	int right[]=new int[15];
	int reverse[]=new int[15];
	final int ROW=8;
	final int COLUMN=8;
	int sum=0;
	public void initPosition(String position[][],int columns,int rows)
	{
		for(int i=0;i<rows;i++)
			for(int j=0;j<columns;j++)
				position[i][j]="○";
		for(int i=0;i<column.length;i++)
			column[i]=0;
		for(int i=0;i<right.length;i++)
		{
			right[i]=0;
			reverse[i]=0;
		}
	}
	public void printPosition(int sum,int column,int row)
	{
		System.out.println(sum);
		for(int i=0;i<row;i++)
		{
			for(int j=0;j<column;j++)
				System.out.print(position[i][j]);
			System.out.println();
		}
	}
	public void getQueenPositions(int i)
	{

		for(int icolumn=0;icolumn<ROW;icolumn++)
		{
			if((column[icolumn]==0)&&(right[i-icolumn+7]==0)&&(reverse[i+icolumn]==0))
			{
				position[i][icolumn]="●";
				column[icolumn]=1;
				right[i-icolumn+7]=1;
				reverse[i+icolumn]=1;
				if(i<7)
					getQueenPositions(i+1);
				else
				{
					printPosition(++sum,ROW,COLUMN);
				}
				position[i][icolumn]="○";
				column[icolumn]=0;
				right[i-icolumn+7]=0;
				reverse[i+icolumn]=0;
			}
		}
	}
	public static void main(String[] args)
	{
		// TODO Auto-generated method stub

		EightQueens_03 demo = new EightQueens_03();
		System.out.println(System.currentTimeMillis());
		demo.initPosition(demo.position, demo.ROW, demo.COLUMN);
		demo.getQueenPositions(0);
		System.out.println(System.currentTimeMillis());
		
	}

}