spoj 1029 Matrix Summation

 1 #include <stdio.h>
 2 #include <string.h>
 3 #include <algorithm>
 4 using namespace std;
 5 const int N = 1030;
 6 int a[N][N];
 7 int c[N][N];
 8 int n;
 9 int lowbit(int x)
10 {
11     return x&(-x);
12 }
13 void add(int x,int y,int ch)
14 {
15     for (int i = x;i <= n;i += lowbit(i))
16     {
17         for (int j = y;j <= n;j += lowbit(j))
18         {
19             c[i][j] += ch;
20         }
21     }
22 }
23 int getsum(int x,int y)
24 {
25     int ans = 0;
26     for (int i = x;i > 0;i -= lowbit(i))
27     {
28         for (int j = y;j > 0;j -= lowbit(j))
29         {
30             ans += c[i][j];
31         }
32     }
33     return ans;
34 }
35 int main()
36 {
37     int T;
38     scanf("%d",&T);
39     while (T--)
40     {
41         memset(c,0,sizeof(c));
42         memset(a,0,sizeof(a));
43         scanf("%d",&n);
44         char s[5];
45         while (scanf("%s",s) != EOF)
46         {
47             if (s[1] == ‘N‘) break;
48             if (s[1] == ‘E‘)
49             {
50                 int x,y,num;
51                 scanf("%d%d%d",&x,&y,&num);
52                 x++,y++;
53                 int ch = num - a[x][y];
54                 a[x][y] = num;
55                 add(x,y,ch);
56             }
57             if (s[1] == ‘U‘)
58             {
59                 int x,y,p,q;
60                 scanf("%d%d%d%d",&x,&y,&p,&q);
61                 x++,y++,p++,q++;
62                 int ans = 0;
63                 ans += getsum(p,q);
64                 ans -= getsum(x-1,q);
65                 ans -= getsum(p,y-1);
66                 ans += getsum(x-1,y-1);
67                 printf("%d\n",ans);
68             }
69         }
70     }
71     return 0;
72 }