P2068 统计和（树状数组模板）

这是一道树状数组题

#include<iostream>
using namespace std;

const int maxn = 1e5 + ;
int tree[maxn], n, m;
char h;
int x, y;
void add(int k, int num){
    while (k <= n){ tree[k] += num; k += k&-k; }
}
int sum(int k){
    int sum = ;
    while (k){
        sum += tree[k];
        k -= k&-k;
    }
    return sum;
}

int main(){
    cin >> n >> m;
    while (m--){
        cin >> h >> x >> y;
        if (h == 'x')add(x, y);
        else cout << sum(y) - sum(x - ) << endl;
    }
}