UVa 10285 Longest Run on a Snowboard

UVa 10285 Longest Run on a Snowboard

题目大意：找到一个最长的下降序列。
典型的记忆化搜索。
以下是我的代码：

#include < stdio.h >
const   long  maxn = 107 ;
char  name[maxn];
long  r,c,h[maxn][maxn],d[maxn][maxn];
const   long  xd[] = { - 1 , 0 , 1 , 0 },yd[] = { 0 , 1 , 0 , - 1 };
long  max( long  a, long  b)
{
     return  (a > b ? a:b);
}
long  dp( long  x, long  y)
{
     if (d[x][y] !=- 1 )
       return  d[x][y];
    d[x][y] = 1 ;
     for ( long  k = 0 ;k < 4 ;k ++ )
    {
        long  xx = x + xd[k],yy = y + yd[k];
        if (xx >= 1 && xx <= r && yy >= 1 && yy <= c && h[xx][yy] < h[x][y])
         d[x][y] = max(d[x][y],dp(xx,yy) + 1 );
    }
     return  d[x][y];
}
int  main()
{
     long  test;
    scanf( " %ld " , & test);
     while (test -- )
    {
       scanf( " %s%ld%ld " ,name, & r, & c);
        for ( long  i = 1 ;i <= r;i ++ )
          for ( long  j = 1 ;j <= c;j ++ )
           scanf( " %ld " , & h[i][j]);
        for ( long  i = 0 ;i <= r + 1 ;i ++ )
          for ( long  j = 0 ;j <= c + 1 ;j ++ )
           d[i][j] =- 1 ;
        long  ans = 0 ;
        for ( long  i = 1 ;i <= r;i ++ )
          for ( long  j = 1 ;j <= c;j ++ )
           ans = max(ans,dp(i,j));
       printf( " %s: %ld\n " ,name,ans);
    }
return   0 ;
}