树状数组Binary Indexed Tree(1):单点修改，区间查询

Description:

给定数列a[1],a[2]…,a[n],需要依次执行q个操作。
操作分两类：
1 i x : 将a[i]加上x
2 l r ：给定l，r，求 ∑ i = l r \sum_{i=l}^r ∑i=lr​a[i]的值
(1 ≤ \leq ≤ n,q ≤ \leq ≤ 10⁶)

代码

// TSWorld
#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 1000009;

long long tree[N];
long long number[N];
int n,q;

inline int lowbit(int x) {
	return x&(-x);
}
void Change(int index,long long delta) {
	while(index <= n) {
		tree[index] += delta;
		index += lowbit(index);
	}
}

long long Query(int index)
{
	long long sum = 0;

	while(index > 0) {
		sum += tree[index];
		index -= lowbit(index);
	}
	return sum;
}
int main()
{
	int cmd = 0,l = 0,r = 0;
	cin>>n>>q;

	for(int i = 1;i <= n;i++) {
		scanf("%lld",&number[i]);
		Change(i,number[i]);
	}

	for(int i = 1;i <= q;i++) {
		scanf("%d%d%d",&cmd,&l,&r);

		if(cmd == 1)
			Change(l,r);
		else
			printf("%lld\n",Query(r) - Query(l-1));
	}

	return 0;
}