算法训练 王、后传说

import java.math.BigInteger;
import java.util.Arrays;
import java.util.Scanner;


public class Main {
    static int n;
    static int[] zhu ;
    static int[] fu;
    static int[] lie;
    static int[][] a;
    static int sum = 0;
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        n = input.nextInt();
        int x = input.nextInt();
        int y = input.nextInt();
        fu = new int[2*n];
        zhu = new int[2*n];
        lie = new int[n+1];
        a = new int[n+2][n+2];
        a[x][y] = 1;
        a[x][y-1] = 1;
        a[x][y+1] = 1;
        a[x+1][y] = 1;
        a[x+1][y-1] = 1;
        a[x+1][y+1] = 1;
        a[x-1][y] = 1;
        a[x-1][y-1] = 1;
        a[x-1][y+1] = 1;
        //i+j-1;
        //j-i+n;
        f(1);
        System.out.println(sum);
    }
    public static  void f(int i){
        for(int j=1;j<=n;j++){
            if(a[i][j]==1||lie[j]==1||fu[i+j-1]==1||zhu[j-i+n]==1)
            continue;
            lie[j] = 1; fu[i+j-1] = 1;zhu[j-i+n] = 1;
            if(i==n){
                sum++;
            }else{
                f(i+1);
            }
            lie[j] = 0;fu[i+j-1] = 0;zhu[j-i+n] = 0;
        }
        
    }
    
    
}