poj_1195Mobile phones,二维树状数组

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int a[1300][1300];
int s;
int lowbit(int x)
{
    return x&(-x);
}
void add(int x,int y,int d)
{
   for(int i=x;i<=s;i+=lowbit(i))
    for(int j=y;j<=s;j+=lowbit(j))
    a[i][j]+=d;
}
int sum(int x,int y)
{
    int ret=0;
    for(int i=x;i>0;i-=lowbit(i))
        for(int j=y;j>0;j-=lowbit(j))
        ret+=a[i][j];
    return ret;
}
int main()
{
    while(scanf("%d%d",&s,&s)!=EOF)
    {
        memset(a,0,sizeof(a));
        int n,x,y,d,xt,yt;
        while(scanf("%d",&n))
        {
            if(n==3) break;
            if(n==1)
            {
                scanf("%d%d%d",&x,&y,&d);
                x++,y++;
                add(x,y,d);
            }
            if(n==2)
            {
                scanf("%d%d%d%d",&x,&y,&xt,&yt);
                x++,y++,xt++,yt++;
                int ans=sum(xt,yt)-sum(xt,y-1)-sum(x-1,yt)+sum(x-1,y-1);
                cout<<ans<<endl;
            }
        }
    }
    return 0;
}