hdu2642二维树状数组，单点修改+区间查询

题目链接：http://icpc.njust.edu.cn/Problem/Hdu/2642/

代码如下：

 #include<bits/stdc++.h>
 using namespace std;
 #define scan(n) scanf("%d",&n)
 #define f(i,a,b) for(int i=a;i<=b;i++)
 #define pf printf
 #define maxn 1005
 int c[maxn][maxn];
 int lowbit(int x)
 {
     return x&(-x);
 }
 void update(int x,int y,int C)
 {
     for(int i=x;i<maxn;i+=lowbit(i))
     {
         for(int j=y;j<maxn;j+=lowbit(j))
         {
             c[i][j]+=C;
         }
     }
 }
 int query(int x,int y)
 {
     int ans=;
     for(int i=x;i;i-=lowbit(i))
     {
         for(int j=y;j;j-=lowbit(j))
         {
             ans+=c[i][j];
         }
     }
     return ans;
 }
 int query(int x,int y,int xx,int yy)
 {
     return query(xx,yy)+query(x-,y-)-query(x-,yy)-query(xx,y-);
 }
 int main()
 {
     int n;
     //freopen("input.txt","r",stdin);
     //freopen("output.txt","w",stdout);
     scan(n);
     char s[];
     int x,y,xx,yy;
     while(n--)
     {
         scanf("%s",&s);
         if(s[]=='B')
         {
             scan(x);
             scan(y);
             x++;y++;
             if(query(x,y,x,y))continue;
             update(x,y,);
         }
         else if(s[]=='D')
         {
             scan(x);
             scan(y);
             x++,y++;
             if(!query(x,y,x,y))continue;
             update(x,y,-);
         }
         else if(s[]=='Q')
         {
             scanf("%d%d%d%d",&x,&xx,&y,&yy);
             if(x>xx)swap(x,xx);
             if(y>yy)swap(y,yy);
             x++,y++,xx++,yy++;
             pf("%d\n",query(x,y,xx,yy));
         }
     }
 }