hdu 2642

这题应该就是标准的二维树状数组，应该没什么难度

处理一下x,y等于0的情况就过了

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
using namespace std;
const int maxn = 1e3+10;
int c[maxn][maxn];
bool map[maxn][maxn];
void add(int x,int y,int d);
int getsum(int x,int y);
int main()
{
    int t,x1,y1,x2,y2;
    while(scanf("%d",&t) != EOF)
    {
        memset(c, 0, sizeof(c));
        memset(map, false, sizeof(map));
        while(t--)
        {
            string a;
            cin >> a;
            if(a == "B")
            {
                scanf("%d%d",&x1,&y1);
                x1 ++; y1 ++;
                if(map[x1][y1])
                    continue;
                add(x1, y1, 1);
                map[x1][y1] = true;
            }
            else if(a == "D")
            {
                scanf("%d%d",&x1,&y1);
                x1 ++; y1 ++;
                if(!map[x1][y1])
                    continue;
                add(x1, y1, -1);
                map[x1][y1] = false;
            }
            else
            {
                scanf("%d%d%d%d",&x1,&x2,&y1,&y2);
                x1 ++; y1 ++; x2 ++; y2 ++;
                if(x1>x2)swap(x1,x2);
                if(y1>y2)swap(y1,y2);
                int k = getsum(x2, y2) + getsum(x1-1, y1-1) - getsum(x1-1,y2) - getsum(x2, y1-1);
                printf("%d\n",k);
            }
        }
    }
    
}
int lowbit(int k)
{
    return k&(-k);
}
void add(int x,int y,int d)
{
    int i,j;
    for(i=x;i<maxn;i+=lowbit(i))
    {
        for(j=y;j<maxn;j+=lowbit(j))
        {
            c[i][j] += d;
        }
    }
}
int getsum(int x,int y)
{
    int i,j;
    int sum = 0;
    for(i=x;i>0;i-=lowbit(i))
        for(j=y;j>0;j-=lowbit(j))
            sum += c[i][j];
    return sum;
}