> import java.io.*;
> import java.util.*;
> 
> public class Main {
> 
> 	public static int[][] dir = {{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};
> 	public static int times;
> 	public static int m,n;
> 	public static boolean[][] flag = new boolean[50][50];
> 	public static boolean tag;
> 	public static int[] tracex = new int[50];
> 	public static int[] tracey = new int[50];
> 	public static void DFS(int i, int j)
> 	{
> 		if(tag) return;
> 		int x,y;
> 		times++;
> 		tracex[times] = i;
> 		tracey[times] = j;
> 		if(times == m*n)
> 		{
> 			tag = true;
> 			return;
> 		}
> 		flag[i][j] = false;
> 		for(int p=0;p<8;p++)
> 		{
> 			x = i+dir[p][1];
> 			y = j+dir[p][0];
> 			if(x>0&&x<=m&&y>0&&y<=n&&flag[x][y])
> 			{
> 				DFS(x,y);
> 				times--;
> 			}
> 		}
> 		flag[i][j]=true;
> 	}
> 	
> 	public static void main(String[] args) 
> 	{
> 		int i,j,k;
> 		Scanner cin = new Scanner(new BufferedInputStream(System.in));
> 		int count = cin.nextInt();
> 		for(i=1;i<=count;i++)
> 		{
> 			times = 0;
> 			tag = false;
> 			m = cin.nextInt();
> 			n = cin.nextInt();
> 			for(k=1;k<50;k++)
> 				for(j=1;j<50;j++)
> 					flag[k][j]=true;
> 			DFS(1,1);
> 			System.out.println("Scenario #" + i +":");
> 			if(tag)
> 			{
> 				for(j=1;j<=m*n;j++)
> 				{
> 					char c = (char) (tracey[j]+64);
> 					System.out.print(c);
> 					System.out.print(tracex[j]);
> 				}
> 				System.out.println();
> 			}
> 			else
> 				System.out.println("Impossible");
> 			if(i!=count)
> 				System.out.println();
> 		}
> 	}
> 
> }
你“Impossible”确定打对了么？。。我看怎么都是小写