MATSUM-Matrix Summation

Matrix Summation

Given below code is for MATSUM or matrix summation .

Hint :- Use 2-D Binary Index Tree (read from top coder tutorial.

#include <bits/stdc++.h>
using namespace std;
#define LL long long 
LL tree[1050][1050];
void update(int x,int y,int val,int MAX)
{
    while(x<=MAX)
    {
        int ty = y;
        while(ty <= MAX)
        {
            tree[x][ty] += val;
            ty += (ty & -ty);
        }
        x += (x & -x);
    }
}
LL read(int x,int y)
{
    LL sum = 0;
    while( x )
    {
        int ty = y;
        while( ty )
        {
            sum += tree[x][ty];
            ty -= (ty & -ty);
        }
        x -= (x & -x);
    }
    return sum;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {
        int n;
        scanf("%d",&n);
        memset(tree,0,sizeof tree);
        while(1)
        {
            char s[10];
            scanf("%s",s);
            if(s[1] == 'E'){
                int x,y,val;
                scanf(" %d%d%d",&x,&y,&val);
                LL p_val = read(x+1,y+1) + read(x,y) - read(x+1,y) - read(x,y+1);
                update(x+1,y+1,val - p_val,n+9);
            }
            else if(s[1] == 'U')
            {
                LL sum = 0;
                int x1,y1,x,y;
                scanf(" %d%d%d%d",&x,&y,&x1,&y1);
                sum = read(x1+1,y1+1) + read(x,y) - read(x,y1+1) - read(x1+1 , y);
                printf("%lld\n",sum);
            }
            else{
                //printf("\n");
                break;
            }
        }
        printf("\n");
    }
    return 0;
}