BIT树状数组

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 1 #ifdef unix
 2 #define LLD "%lld"
 3 #else
 4 #define LLD "%I64d"
 5 #endif
 6 #include <cstdio>
 7 #include <cstring>
 8 #include <cstdlib>
 9 #include <cmath>
10 #include <algorithm>
11 #include <iostream>
12 #include <vector>
13 #include <stack>
14 #include <queue>
15 #include <map>
16 #define LL long long
17 #define maxn 100000
18 #define INF 1 << 30
19 #define For(i, n) for (int i = 1; i <= n; i++)
20 #define rep(i, j, k) for (int i = j; i <= k; i++)
21 #define lson l, mid, rt << 1
22 #define rson mid + 1, r, rt << 1 | 1
23 using namespace std;
24 int n, m, a[maxn];
25 struct BIT {
26     int lowbit(int x) {return x & -x;}
27     void modify(int x, int data) {while (x <= n) a[x] += data, x += lowbit(x);}
28     int sum(int x) {
29         int tot = 0;
30         while (x > 0) tot+=a[x], x -= lowbit(x);
31         return tot;
32     }
33 }bit;
34 int main() {
35     int x, y;
36     memset(a, 0, sizeof(a));
37     scanf("%d%d", &n, &m);
38     For(i, n) {
39         scanf("%d", &x);
40         bit.modify(i, x);
41     }
42     For(i, m) {
43         scanf("%d%d", &x, &y);
44         printf("%d\n", bit.sum(y) - bit.sum(x - 1));
45     }
46     return 0;
47 }

 

相关题目

1、 BZOJ 2743: [HEOI2012]采花

题目：http://61.187.179.132/JudgeOnline/problem.php?id=2743

题解，代码：http://www.cnblogs.com/joker0429/archive/2013/02/10/2909874.html

posted @ 2013-02-10 20:32  Joker0429  阅读(139)  评论(0)  编辑  收藏  举报