题目链接： http://poj.org/problem?id=2488
被字典序弄疯了，干脆枚举所有情况，然后找个字典序最小的吧。。不过代码还是很短的。
1 #include <stdio.h> 2 #include <string.h> 3 4 struct Point 5 { 6 int x, y; 7 }; 8 9 int map[30][30], n, m; 10 const int dir[8][2] = {{-1, -2}, {1, -2}, {-2, -1}, {2, -1}, {-2, 1}, {2, 1}, {-1, 2}, {1, 2}}; 11 bool vis[30][30]; 12 char path[60], ans[60]; 13 14 void dfs(int x, int y, int cnt) 15 { 16 vis[x][y] = 1; 17 path[cnt++] = y + 'A' - 1; 18 path[cnt++] = x + '0'; 19 if(cnt / 2 == n*m) 20 { 21 path[cnt] = 0; 22 if(ans[0] == 0 || strcmp(path, ans) < 0) 23 strcpy(ans, path); 24 } 25 for(int i = 0; i < 8; i++) 26 { 27 int nx = x + dir[i][0]; 28 int ny = y + dir[i][1]; 29 if(nx > 0 && nx <= n && ny > 0 && ny <= m && !vis[nx][ny]) 30 dfs(nx, ny, cnt); 31 } 32 vis[x][y] = 0; 33 } 34 35 int main() 36 { 37 int t; 38 scanf("%d", &t); 39 for(int i = 1; i <= t; i++) 40 { 41 scanf("%d %d", &n, &m); 42 printf("Scenario #%d: ", i); 43 memset(vis, 0, sizeof(vis)); 44 ans[0] = 0; 45 dfs(1, 1, 0); 46 if(ans[0] == 0) 47 printf("impossible "); 48 else 49 printf("%s ", ans); 50 } 51 return 0; 52 }