HDU 1892 See you~

HDU 1892 See you~

二维树状数组问题。
以下是我的代码：

#include < iostream >
#include < string >
#include < algorithm >
#include < cstdio >
#include < cstring >
#define  lowbit(x) ((x)&(-(x)))
using   namespace  std;
const   int  kMaxn( 1001 );

int  bit[kMaxn + 7 ][kMaxn + 7 ],book[kMaxn + 7 ][kMaxn + 7 ];

void  Add( int  x, int  y, int  delta)
{
     for ( int  i = x;i <= kMaxn;i += lowbit(i))
         for ( int  j = y;j <= kMaxn;j += lowbit(j))
            bit[i][j] += delta;
}

int  Sum( int  x, int  y)
{
     int  re( 0 );
     for ( int  i = x;i > 0 ;i -= lowbit(i))
         for ( int  j = y;j > 0 ;j -= lowbit(j))
            re += bit[i][j];
     return  re;
}

int  main()
{
     int  T;
    scanf( " %d " , & T);
     for ( int  case_num = 1 ;case_num <= T;case_num ++ )
    {
        printf( " Case %d:\n " ,case_num);
        memset(bit, 0 , sizeof (bit));
        memset(book, 0 , sizeof (book));

         for ( int  i = 1 ;i <= kMaxn;i ++ )
             for ( int  j = 1 ;j <= kMaxn;j ++ )
            {
                Add(i,j, 1 );
                book[i][j] = 1 ;
            }

         int  Q;
        scanf( " %d " , & Q);
         while (Q -- )
        {
             string  cmd;
            cin >> cmd;
             if (cmd == " S " )
            {
                 int  x1,y1,x2,y2;
                scanf( " %d%d%d%d " , & x1, & y1, & x2, & y2);
                x1 ++ ;y1 ++ ;x2 ++ ;y2 ++ ;
                 if (x1 > x2)
                    swap(x1,x2);
                 if (y1 > y2)
                    swap(y1,y2);
                printf( " %d\n " ,Sum(x2,y2) - Sum(x1 - 1 ,y2) - Sum(x2,y1 - 1 ) + Sum(x1 - 1 ,y1 - 1 ));
            }
             else   if (cmd == " A " )
            {
                 int  x,y,n1;
                scanf( " %d%d%d " , & x, & y, & n1);
                x ++ ;y ++ ;
                Add(x,y,n1);
                book[x][y] += n1;
            }
             else   if (cmd == " D " )
            {
                 int  x,y,n1;
                scanf( " %d%d%d " , & x, & y, & n1);
                x ++ ;y ++ ;
                Add(x,y,(book[x][y] - n1 < 0 ?- book[x][y]: - n1));
                book[x][y] = (book[x][y] - n1 < 0 ? 0 :book[x][y] - n1);
            }
             else   if (cmd == " M " )
            {
                 int  x1,y1,x2,y2,n1;
                scanf( " %d%d%d%d%d " , & x1, & y1, & x2, & y2, & n1);
                x1 ++ ;y1 ++ ;x2 ++ ;y2 ++ ;
                 if (book[x1][y1] > n1)
                {
                    Add(x1,y1, - n1);
                    Add(x2,y2,n1);
                    book[x1][y1] -= n1;
                    book[x2][y2] += n1;
                }
                 else
                {
                    Add(x1,y1, - book[x1][y1]);
                    Add(x2,y2,book[x1][y1]);
                    book[x2][y2] += book[x1][y1];
                    book[x1][y1] = 0 ;
                }
            }
        }
    }

     return   0 ;
}