poj 1195 Mobile phones

http://poj.org/problem?id=1195

#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxn 1026
using namespace std;

int a[maxn][maxn];
int c[maxn][maxn];
int S,x,y,aa,l,r,b,t,h,T;

int lowbit(int x)
{
    return x&(x^(x-1));
}

void update(int i,int j,int k)
{
    while(i<=S)
    {
        int temp=j;
        while(temp<=S)
        {
            c[i][temp]+=k;
            temp+=lowbit(temp);
        }
        i+=lowbit(i);
    }
}

int sum(int i,int j)
{
    int sum1=0;
    while(i>0)
    {
        int temp=j;
        while(temp>0)
        {
            sum1+=c[i][temp];
            temp-=lowbit(temp);
        }
        i-=lowbit(i);
    }
    return sum1;
}

int main()
{
    while(scanf("%d",&h))
    {
        if(h==0)
        {
            scanf("%d",&S);
            memset(c,0,sizeof(c));
        }
        else if(h==3) break;
        else if(h==1)
        {
            scanf("%d%d%d",&x,&y,&aa);
            update(x+1,y+1,aa);
        }
        else if(h==2)
        {
            scanf("%d%d%d%d",&l,&r,&b,&t);
            int sum1=sum(b+1,t+1);
            int sum2=sum(l,t+1);
            int sum3=sum(b+1,r);
            int sum4=sum(l,r);
            printf("%d\n",sum1-sum2-sum3+sum4);
        }
    }
    return 0;
}