树状数组之二

//poj 1195 Mobile phones

#include <iostream>            //简单二维树状数组
using namespace std;
int table[1025][1025];    //初始化为0
int S,X,Y,A,L,B,R,T,side;
int lowbit(int x)
{
    return x&(-x);
}
void modify(int x,int y,int a)
{
    x++;y++;        //使得表下标的最小值从1而不是从0开始
    while(x<=side)
    {
        int j=y;
        while(j<=side)
        {
            table[x][j]+=a;
            j+=lowbit(j);
        }
        x+=lowbit(x);
    }
}
int sum(int x,int y)
{
    x++;y++;
    int s=0;
    while(x>0)
    {
        int j=y;
        while(j>0)
        {
            s+=table[x][j];
            j-=lowbit(j);
        }
        x-=lowbit(x);
    }
    return s;
}
int main()
{
    int d,s;
    while(scanf("%d",&d))
    {
        switch (d)
        {
            case 0:
                scanf("%d",&side);break;
            case 1:
                scanf("%d%d%d",&X,&Y,&A);
                modify(X,Y,A);
                break;
            case 2:
                scanf("%d%d%d%d",&L,&B,&R,&T);
                s=sum(R,T)-sum(L-1,T)-sum(R,B-1)+sum(L-1,B-1);
                printf("%d\n",s);
                break;
            default:
                break;
        }
        if(d==3)
            break;
    }
    return 0;
}