poj 1195

树状数组，因为此是求二维数组的区间的和，所以将其扩展为二维树状数组

#include <stdio.h>
#include <memory.h>
const int maxn=1100;
int c[maxn][maxn];
int n;
int LowBit(int x)
{
	return x&(x^(x-1));
}
void Update(int x,int y,int a)
{
	for(int i=x;i<=n;i+=LowBit(i))
		for(int j=y;j<=n;j+=LowBit(j))
			c[i][j]+=a;
}
int getSum(int x,int y)
{
	int i,j,sum=0;
	for(i=x;i>0;i=i-LowBit(i))
	{
		for(j=y;j>0;j-=LowBit(j))
		{
			sum+=c[i][j];
		}
	}
	return sum;
}
int main()
{
	int in,x,y,a,l,b,r,t;
	while(scanf("%d",&in)&&in!=3)
	{		
		if(in==0)
		{
			scanf("%d",&n);
			memset(c,0,sizeof(c));
		}
		else if(in==1)
		{
			scanf("%d%d%d",&x,&y,&a);
			Update(x+1,y+1,a);
		}
		else
		{
			scanf("%d%d%d%d",&l,&b,&r,&t);
			int acount=getSum(r+1,t+1)-getSum(l+1-1,t+1)-getSum(r+1,b+1-1)+getSum(l+1-1,b+1-1);
			printf("%d\n",acount);
		}
	}
	return 0;
}