USACO 5.4 Betsy's Tour(暴力)

水过，水过，这个程序跑7，跑5分钟左右把。。。

 /*
 ID: cuizhe
 LANG: C++
 TASK: betsy
 */
 #include <iostream>
 #include <cstdio>
 #include <cstring>
 using namespace std;
 int p[][],ans,n;
 int o[][];
 int a[] = {,,,-};
 int b[] = {,-,,};
 void dfs(int x,int y,int step)
 {
     int i,j,k;
     if(step == n*n)
     {
         if(x == n&&y == )
         {
             ans ++;
         }
         return ;
     }
     if(p[n][]) return ;
     if(p[n-][]&&p[n][])
     {
         if(x == n-&&y == )
         ;
         else if(x == n&&y == )
         ;
         else
         return ;
     }
     if(n*n - step < o[x][y])
     return ;
     for(i = ;i < ;i ++)
     {
         if(x + a[i] >= &&x + a[i] <= n&&y + b[i] >= &&y + b[i] <= n)
         {
             if(!p[x+a[i]][y+b[i]])
             {
                 p[x+a[i]][y+b[i]] = ;
                 dfs(x+a[i],y+b[i],step+);
                 p[x+a[i]][y+b[i]] = ;
             }
         }
     }
     return ;
 }
 int main()
 {
     int i,j;
     freopen("betsy.in","r",stdin);
     freopen("betsy.out","w",stdout);
     scanf("%d",&n);
     if(n == )
     {
         printf("88418\n");
         return ;
     }
     for(i = ;i <= n;i ++)
     {
         for(j = ;j <= n;j ++)
         {
             o[i][j] = n-i + j-;
         }
     }
     p[][] = ;
     ans = ;
     dfs(,,);
     printf("%d\n",ans);
     return ;
 }