N皇后问题可视化实现（java）

package queens;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.Image;
import java.io.IOException;
import java.util.Scanner;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;

class scan {
	public static Scanner instance = new Scanner(System.in);
}

class queen{
	ImageIcon image = new ImageIcon("queen.png");//JLabel的皇后图标
	public int num = 0;	//皇后数量
	public int sum = 0;	//解的计数器
	public int set = 0;	//落子次数
	public int[] a;
	
	JFrame frame = new JFrame("棋盘");
	JLabel lab[][] = null;
	Scanner s;
	
	//构造函数，初始化问题的规模
	queen(){
		System.out.print("请输入皇后数量：");
		s = scan.instance;
		num = s.nextInt();
		sum = 0;
		a = new int[num];	 
	}
	
	queen(int n){
		num = n;
		sum = 0;
		a = new int[num];	 
	}
	
	//不带可视化计时间的n皇后回溯
	public void backtrack(int t){	
		if (t >= num){
			sum++;				//解数++			
		}
		else{
			for(int j = 0;j < num ;j++){			
				a[t] = j;		//假设第t行第j列放棋子
				if (place(t)) {	//是否落子
					set++;		//落子步数++
					backtrack(t+1);	//落子，进入下一深度			//递归调用
				}	
			}
		}
	}
	
	//带可视化不计时间的n皇后
	public void bbacktrack(int t){	
		if (t >= num){			//判断是否超出棋盘大小
			sum++;
			for(int i = 0;i < num; i++){
				System.out.print(a[i] + " "); 
			}
			System.out.println();						
			try {
				Thread.sleep(1000);			//休眠1s
			} catch (InterruptedException e) {	
				e.printStackTrace();
			}
		}
		else{
			for(int j = 0;j < num ;j++){
				
				a[t] = j;		//先将第t行放入j
				
				if (place(t)) {	//判断是否落子
					try {
						Thread.sleep(500);	//休眠0.1s
					} catch (InterruptedException e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}
					lab[t][a[t]].setIcon(image);	//落子
					bbacktrack(t+1);					//递归调用
				}	
				lab[t][a[t]].setIcon(null);
			}
		}
	}
	
	
	public boolean place(int t){	//判断是否落子，与减枝
		for(int i = 0; i < t;i++){
			//判断是否在同一列
			if(a[i] == a[t]) return false;
			//判断是否在同一斜线
			if((t-i)== Math.abs(a[t]-a[i])) return false;
		}
		return true;
	}
	

	public void chessboard(){		//棋盘绘制
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setSize(500, 500); 
	    frame.setResizable(false);
	    frame.setLocation(200,0);	    
	    Image img = image.getImage();  
        img = img.getScaledInstance(100, 100, Image.SCALE_DEFAULT); 
        image.setImage(img);
	    frame.setVisible(true);  
	    frame.setLayout(new GridLayout(num,num));  
		frame.setSize(num*100, num*100); 
	    frame.setResizable(true);
		lab = new JLabel[num][num];  
		for(int i = 0;i <num;i++){  
	            for(int j = 0;j < num;j++){  
	                lab[i][j] = new JLabel();  
	                lab[i][j].setOpaque(true);//设置为透明，才能显示背景色
	                if((i+j)%2==0){  
	                	lab[i][j].setBackground(Color.gray);
	                }  
	                else{  
	                	lab[i][j].setBackground(Color.white);
	                }  
	                frame.add(lab[i][j]);   
	            }  
	     }  
	}
	

	
};

public class run {
	public static void run_q(int x){
		Scanner s = scan.instance;
		if (x == 0){
			System.out.println("请输入你想要测试的规模：" );	
			int max = scan.instance.nextInt();
			for (int i=1 ;i <= max ;i++){	
				queen q = new queen(i);
				long start = System.nanoTime();
				q.backtrack(0);
				long end = System.nanoTime();
				System.out.print( i + "皇后有" + q.sum + "种解 ，落子步数:" + q.set);
				System.out.println("用时:" + ((end-start)/1000000.000) + "ms");
			}
			
		}
		else if ( x == 1){
			queen q = new queen();
			q.chessboard();
			q.bbacktrack(0);
		}
		else if ( x == 2){
			System.out.print("请输入你想要测试的规模：" );
			int n = s.nextInt();
			boolean flag = true;
			System.out.println("请依此输入你想要的测试数据：");
			queen q = new queen(n);
			for(int i=0 ;i<n;i++)
				q.a[i] = -1;	
			for(int i=0 ;i<n;i++){
				int index = s.nextInt()-1;
				if(q.a[index] == -1){	//判断是否之前有输入这一行的数据，有就直接失败
					q.a[index] = s.nextInt()-1;
					if (!q.place(i)) {flag = false;break;}//判断是否冲突
				}
				else {flag = false; break;}		
			}	
			if(!flag){
			System.out.println("失败");
			}
			else{
				System.out.println("成功");
			}
		}
		
		
	}
	
	public static void run_t() throws InterruptedException{
		
		boolean flag = true;
		while(flag){
			Scanner s = scan.instance;
			System.out.print("请输入数字，0测试计算时间，1代表可视化，2代表数据测试：");
			int x = s.nextInt();
			run_q(x);
			System.out.print("是否继续（y/n）：");
			String c = s.next();
			if( c.equals("n")) flag = false;
			
		}
	}
	 public static void main(String[] args) throws IOException, InterruptedException {
		 	run_t();
		 
	    }   
}