POJ 2488

#include <bits/stdc++.h>
using namespace std;
int visited[30][30];
struct Pos{
	int r, c;
};
Pos path[30];
Pos mov[8] = {{-2, -1}, {-2, 1}, {-1, -2}, {-1, 2}, 
				{1, -2}, {1, 2}, {2, -1}, {2, 1}};
int p, q;
bool DFS(int r, int c, int steps);
int main()
{
	int t;
//	scanf("%d", &t);
	cin >> t;
	int i, j, k;
	int m;
	for(i = 1; i <= t; i++){
		
		printf("Scenario #%d:\n", i);
		
//		scanf("%d%d", &p, &q);
		cin >> p >> q;		
		memset(visited, 0, sizeof(visited));
		for(j = 0; j < q; j++){
			for(k = 0; k < p; k++){
				
				if(DFS(j, k, 0)){
					j = q + 10;	
					for(m = 0; m < p*q; m++){
						printf("%c%d", path[m].r + 'A', path[m].c + 1);
					}	
					break;
				}
			
			}
		}
		
		if(j == q) printf("impossible");
		printf("\n\n"); 
		
	}
	
	return 0; 
}
bool DFS(int r, int c, int steps)
{
	if(steps == p*q) return true;
	if(r < 0 || c < 0 || r >= q || c >= p) return false;
	if(visited[r][c]) return false;
	
	int i;
	visited[r][c] = 1;
	path[steps].r = r;
	path[steps].c = c;
	for(i = 0; i < 8; i++){
		if(DFS(r + mov[i].r, c + mov[i].c, steps + 1)) return true; 
	} 
	visited[r][c] = 0;
	
	return false;
}