HDU 1541 Stars

HDU 1541 Stars

题目已经说明了按Y值递增的顺序给出，Y值相同则按X递增给出。如果不是这样可以先排序，然后用树状数组解决。
以下是我的代码：

#include < cstdio >
#include < cstring >
#define  lowbit(x) ((x)&(-(x)))
using   namespace  std;
const   int  kMaxn( 15007 );
const   int  kMaxx( 32001 );

int  bit[kMaxx + 7 ],level[kMaxn];

void  Add( int  pos, int  delta)
{
     for ( int  i = pos;i <= kMaxx;i += lowbit(i))
        bit[i] += delta;
}

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

int  main()
{
     int  n;
     while (scanf( " %d " , & n) == 1 )
    {
        memset(bit, 0 , sizeof (bit));
        memset(level, 0 , sizeof (level));

         for ( int  i = 1 ;i <= n;i ++ )
        {
             int  x,y;
            scanf( " %d%d " , & x, & y);
            level[Sum(x + 1 )] ++ ;
            Add(x + 1 , 1 );
        }

         for ( int  i = 0 ;i < n;i ++ )
            printf( " %d\n " ,level[i]);
    }

     return   0 ;
}