- 场景：快速得到一段数组元素的和
- 题目：Insertion Sort Advanced Analysis | HackerRank
- 算法：binary-indexed-tree :: HackerRank
- 实现：binary-indexed-tree :: HackerRank 已经给出基本的实现了
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
// get cumulative sum up to and including i
int Get(int i) {
int res = 0;
while(i) {
res += B[i];
i -= (i & -i);
}
return res;
}
// add val to value at i
void Set(int i, int val) {
while(i <= N) {
B[i] += val;
i += (i & -i);
}
}