回溯法求八皇后排列方法

代码如下：

import java.util.ArrayList;

public class BHH {
    static int count = 0;
    static boolean vis[][] = new boolean[3][30];
    public static void main(String[] args){
        ArrayList<Integer> resu = new ArrayList<>();
        BB(1,resu);
        System.out.println(count);
    }
    
    public static void BB(int cur,ArrayList<Integer> b){
        if(cur == 9){
            count++;
            show(new ArrayList<>(b));
            return;
        }
        for(int i =1 ;i <=8;i++){
            if(!vis[0][i] && !vis[1][cur-i+8] && !vis[2][cur+i]){
                b.add(i);
                vis[0][i] = vis[1][cur-i+8] = vis[2][cur+i] = true;
                BB(cur+1,b);
                b.remove(b.size() - 1);
                vis[0][i] = vis[1][cur-i+8] = vis[2][cur+i] = false;
            }
        }
    }
    public static void show(ArrayList<Integer> b){
        System.out.println(b);
    }
}

打印结果如下

[1, 5, 8, 6, 3, 7, 2, 4]
[1, 6, 8, 3, 7, 4, 2, 5]
[1, 7, 4, 6, 8, 2, 5, 3]
[1, 7, 5, 8, 2, 4, 6, 3]
[2, 4, 6, 8, 3, 1, 7, 5]
[2, 5, 7, 1, 3, 8, 6, 4]
[2, 5, 7, 4, 1, 8, 6, 3]
[2, 6, 1, 7, 4, 8, 3, 5]
[2, 6, 8, 3, 1, 4, 7, 5]
[2, 7, 3, 6, 8, 5, 1, 4]
[2, 7, 5, 8, 1, 4, 6, 3]
[2, 8, 6, 1, 3, 5, 7, 4]
[3, 1, 7, 5, 8, 2, 4, 6]
[3, 5, 2, 8, 1, 7, 4, 6]
[3, 5, 2, 8, 6, 4, 7, 1]
[3, 5, 7, 1, 4, 2, 8, 6]
[3, 5, 8, 4, 1, 7, 2, 6]
[3, 6, 2, 5, 8, 1, 7, 4]
[3, 6, 2, 7, 1, 4, 8, 5]
[3, 6, 2, 7, 5, 1, 8, 4]
[3, 6, 4, 1, 8, 5, 7, 2]
[3, 6, 4, 2, 8, 5, 7, 1]
[3, 6, 8, 1, 4, 7, 5, 2]
[3, 6, 8, 1, 5, 7, 2, 4]
[3, 6, 8, 2, 4, 1, 7, 5]
[3, 7, 2, 8, 5, 1, 4, 6]
[3, 7, 2, 8, 6, 4, 1, 5]
[3, 8, 4, 7, 1, 6, 2, 5]
[4, 1, 5, 8, 2, 7, 3, 6]
[4, 1, 5, 8, 6, 3, 7, 2]
[4, 2, 5, 8, 6, 1, 3, 7]
[4, 2, 7, 3, 6, 8, 1, 5]
[4, 2, 7, 3, 6, 8, 5, 1]
[4, 2, 7, 5, 1, 8, 6, 3]
[4, 2, 8, 5, 7, 1, 3, 6]
[4, 2, 8, 6, 1, 3, 5, 7]
[4, 6, 1, 5, 2, 8, 3, 7]
[4, 6, 8, 2, 7, 1, 3, 5]
[4, 6, 8, 3, 1, 7, 5, 2]
[4, 7, 1, 8, 5, 2, 6, 3]
[4, 7, 3, 8, 2, 5, 1, 6]
[4, 7, 5, 2, 6, 1, 3, 8]
[4, 7, 5, 3, 1, 6, 8, 2]
[4, 8, 1, 3, 6, 2, 7, 5]
[4, 8, 1, 5, 7, 2, 6, 3]
[4, 8, 5, 3, 1, 7, 2, 6]
[5, 1, 4, 6, 8, 2, 7, 3]
[5, 1, 8, 4, 2, 7, 3, 6]
[5, 1, 8, 6, 3, 7, 2, 4]
[5, 2, 4, 6, 8, 3, 1, 7]
[5, 2, 4, 7, 3, 8, 6, 1]
[5, 2, 6, 1, 7, 4, 8, 3]
[5, 2, 8, 1, 4, 7, 3, 6]
[5, 3, 1, 6, 8, 2, 4, 7]
[5, 3, 1, 7, 2, 8, 6, 4]
[5, 3, 8, 4, 7, 1, 6, 2]
[5, 7, 1, 3, 8, 6, 4, 2]
[5, 7, 1, 4, 2, 8, 6, 3]
[5, 7, 2, 4, 8, 1, 3, 6]
[5, 7, 2, 6, 3, 1, 4, 8]
[5, 7, 2, 6, 3, 1, 8, 4]
[5, 7, 4, 1, 3, 8, 6, 2]
[5, 8, 4, 1, 3, 6, 2, 7]
[5, 8, 4, 1, 7, 2, 6, 3]
[6, 1, 5, 2, 8, 3, 7, 4]
[6, 2, 7, 1, 3, 5, 8, 4]
[6, 2, 7, 1, 4, 8, 5, 3]
[6, 3, 1, 7, 5, 8, 2, 4]
[6, 3, 1, 8, 4, 2, 7, 5]
[6, 3, 1, 8, 5, 2, 4, 7]
[6, 3, 5, 7, 1, 4, 2, 8]
[6, 3, 5, 8, 1, 4, 2, 7]
[6, 3, 7, 2, 4, 8, 1, 5]
[6, 3, 7, 2, 8, 5, 1, 4]
[6, 3, 7, 4, 1, 8, 2, 5]
[6, 4, 1, 5, 8, 2, 7, 3]
[6, 4, 2, 8, 5, 7, 1, 3]
[6, 4, 7, 1, 3, 5, 2, 8]
[6, 4, 7, 1, 8, 2, 5, 3]
[6, 8, 2, 4, 1, 7, 5, 3]
[7, 1, 3, 8, 6, 4, 2, 5]
[7, 2, 4, 1, 8, 5, 3, 6]
[7, 2, 6, 3, 1, 4, 8, 5]
[7, 3, 1, 6, 8, 5, 2, 4]
[7, 3, 8, 2, 5, 1, 6, 4]
[7, 4, 2, 5, 8, 1, 3, 6]
[7, 4, 2, 8, 6, 1, 3, 5]
[7, 5, 3, 1, 6, 8, 2, 4]
[8, 2, 4, 1, 7, 5, 3, 6]
[8, 2, 5, 3, 1, 7, 4, 6]
[8, 3, 1, 6, 2, 5, 7, 4]
[8, 4, 1, 3, 6, 2, 7, 5]
92