UVa 639 Don't Get Rooked

UVa 639 Don't Get Rooked

数据规模很小，直接搜索即可，每次试着在可以放置的位置上放置。
以下是我的代码：

#include < iostream >
#include < cstdio >
using   namespace  std;
const   int  kMaxn( 7 );

int  n,ans,map[kMaxn][kMaxn];

void  getxy( int  depth, int   & x, int   & y)
{
    x = depth / n;
    y = depth % n;
     if (y)
        x ++ ;
     if ( ! y)
        y = n;
}

bool  check( int  x, int  y)
{
     for ( int  i = y - 1 ;i >= 1   &&  map[x][i] != 2 ;i -- )
         if (map[x][i] == 1 )
             return   false ;
     for ( int  i = y + 1 ;i <= n  &&  map[x][i] != 2 ;i ++ )
         if (map[x][i] == 1 )
             return   false ;
     for ( int  i = x - 1 ;i >= 1   &&  map[i][y] != 2 ;i -- )
         if (map[i][y] == 1 )
             return   false ;
     for ( int  i = x + 1 ;i <= n  &&  map[i][y] != 2 ;i ++ )
         if (map[i][y] == 1 )
             return   false ;
     return   true ;
}

void  dfs( int  depth, int  now)
{
     if (depth > n * n)
    {
         if (ans < now)
            ans = now;
         return ;
    }

     int  x,y;
    getxy(depth,x,y);

    dfs(depth + 1 ,now);
     if ( ! map[x][y]  &&  check(x,y))
    {
        map[x][y] = 1 ;
        dfs(depth + 1 ,now + 1 );
        map[x][y] = 0 ;
    }

}

int  main()
{
     /*
    freopen("data.in","r",stdin);
    freopen("data.out","w",stdout);
    // */

     while (cin >> n  &&  n)
    {
        cin. get ();
         for ( int  i = 1 ;i <= n;i ++ )
             for ( int  j = 1 ;j <= n;j ++ )
            {
                 char  t;
                cin >> t;
                 if (t == ' . ' )
                    map[i][j] = 0 ;
                 else
                    map[i][j] = 2 ;
            }

        ans = 0 ;
        dfs( 1 , 0 );

        cout << ans << endl;
    }

     return   0 ;
}