hdu 1166 敌兵布阵

题目链接：hdu 1166 敌兵布阵

标准的树状数组模板题，需要注意的是树状数组的初始节点的编号为1。

 1 #define     MAX_N 1000007

 2 #include <cstdlib>

 3 #include  <cstdio>

 4 #include  <iostream>

 5 #include <cstring>

 6 using namespace std;

 7 int bit[MAX_N+1], n;

 8 int lowbit(int x)

 9 {

10     return x&(-x);

11 }

12 int sum(int i)

13 {

14     int s = 0;

15     while( i > 0 )

16     {

17         s += bit[i];

18         i -= lowbit(i);

19     }

20     return s;

21 }

22 void add(int i , int x)

23 {

24     while( i <= n )

25     {

26         bit[i] += x;

27         i += lowbit(i);

28     }

29 }

30 int main(int argc, char *argv[])

31 {

32     int T;

33     int c = 1;

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

35     while( T-- )

36     {

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

38         memset(bit, 0, sizeof(bit));

39         for( int i = 1 ; i <= n ; i++ )

40         {

41             int tmp;

42             scanf ( "%d", &tmp );

43             add(i, tmp);

44         }

45         char s[10];

46         int a, b;

47         printf("Case %d:\n", c++);

48         while(1)

49         {

50             scanf("%s", s);

51             if( !strcmp(s , "End" ))

52             {

53                 break;

54             }

55             else

56             {

57                 scanf("%d%d", &a, &b);

58                 if( !strcmp(s,  "Query") )

59                 {

60                     printf("%d\n", sum(b) - sum(a-1));

61                 }

62                 else if(!strcmp( s ,  "Add") )

63                 {

64                     add(a, b);

65                 }

66                 else if(!strcmp(s, "Sub"))

67                 {

68                     add(a, -b);

69                 }

70             }

71         }

72     }

73 }