hdu 1208 Pascal's Travels

http://acm.hdu.edu.cn/showproblem.php?pid=1208

 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #define maxn 100
 #define ll __int64
 using namespace std;

 ll dp[maxn][maxn];
 char g[maxn][maxn];
 int a[maxn][maxn];
 int n;

 ll dfs(int x,int y)
 {
     int xx,yy;
     if(dp[x][y]||(!a[x][y])) return dp[x][y];
     xx=x+a[x][y];
     yy=y;
     if(xx>=&&xx<n&&yy>=&&yy<n)
     {
         dp[x][y]+=dfs(xx,yy);
     }
     xx=x;
     yy=y+a[x][y];
     if(xx>=&&xx<n&&yy>=&&yy<n)
     {
         dp[x][y]+=dfs(xx,yy);
     }
     return dp[x][y];
 }

 int main()
 {
     while(scanf("%d",&n)!=EOF)
     {
         if(n==-) break;
         for(int i=; i<n; i++)
         {
             scanf("%s",g[i]);
             for(int j=; j<n; j++)
             {
                 a[i][j]=g[i][j]-'';
             }
         }
         memset(dp,,sizeof(dp));
         dp[n-][n-]=;
         printf("%I64d\n",dfs(,));
     }
     return ;
 }