SPOJ 1029 Matrix Summation【 二维树状数组 】

题意：二维树状数组，更改值的时候有一点不一样，

是将a[x][y]设置为一个值，所以add的时候要将它和以前的值作差一下

 1 #include<iostream>  

 2 #include<cstdio>  

 3 #include<cstring> 

 4 #include <cmath> 

 5 #include<stack>

 6 #include<vector>

 7 #include<map> 

 8 #include<set>

 9 #include<queue> 

10 #include<algorithm>  

11 using namespace std;

12 

13 typedef long long LL;

14 const int INF = (1<<30)-1;

15 const int mod=1000000007;

16 const int maxn=5005;

17 

18 int a[maxn][maxn];

19 int c[maxn][maxn];//树状数组

20 int n;

21 

22 int lowbit(int x){ return x & (-x);}

23 

24 int sum(int x,int y){

25     int ret=0;

26     int y1;

27     while(x > 0){

28         y1 = y;

29         while(y1 > 0){

30             ret += c[x][y1];y1-=lowbit(y1);

31         }

32         x-=lowbit(x);

33     }

34     return ret;

35 }

36 

37 void add(int x,int y,int d){

38     int y1;

39     while(x < maxn){

40         y1 = y;

41         while (y1 < maxn){

42             c[x][y1]+=d; y1+=lowbit(y1);

43         } 

44         x+=lowbit(x);

45     }

46 }

47 

48 int main(){

49     int T;

50     scanf("%d",&T);

51     while(T--){

52         memset(c,0,sizeof(c));

53         memset(a,0,sizeof(a));

54         scanf("%d",&n);

55         char s[15];

56         while(scanf("%s",s)!=EOF){

57             if(s[0] == 'E') break;

58             if(s[1]=='E'){

59                 int x,y,num;

60                 scanf("%d %d %d",&x,&y,&num);x++;y++;

61                 int tmp = num - a[x][y];

62                 a[x][y] = num;

63                 add(x,y,tmp); 

64             }

65             if(s[1]=='U'){

66                 int x,y,xx,yy;

67                 int ans=0;

68                 scanf("%d %d %d %d",&x,&y,&xx,&yy);

69                 x++;y++;xx++;yy++;

70                 ans = sum(xx,yy) - sum(x-1,yy) - sum(xx,y-1) + sum(x-1,y-1);

71                 printf("%d\n",ans);

72             }

73         }    

74     }

75     return 0;

76 } 

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