poj1195 Mobile phones

裸的二维树状数组

#include<stdio.h>
#include<string.h>
#define maxn 1100
int tree[maxn][maxn];
int lowbit(int x)
{
return x&(-x);
}
void update(int x,int y,int num,int R,int C)
{
int i,j;
for(i=x;i<=R;i+=lowbit(i))
for(j=y;j<=C;j+=lowbit(j))
tree[i][j]+=num;
}
int sum(int x,int y)
{
int i,j,s=0;
for(i=x;i>0;i-=lowbit(i))
for(j=y;j>0;j-=lowbit(j))
s+=tree[i][j];
return s;
}
int getsum(int x1,int y1,int x2,int y2)
{
return sum(x2,y2)-sum(x1-1,y2)-sum(x2,y1-1)+sum(x1-1,y1-1);
}
int main()
{
int op,n;
memset(tree,0,sizeof(tree));
while(scanf("%d",&op),op!=3)
{
if(op==0)
scanf("%d",&n);
else if(op==1)
{
int x,y,a;
scanf("%d%d%d",&x,&y,&a);
update(x+1,y+1,a,n,n);
}
else if(op==2)
{
int l,r,b,t;
scanf("%d%d%d%d",&l,&b,&r,&t);
printf("%d\n",getsum(l+1,b+1,r+1,t+1));

}
}
}