树状数组模板

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1000 + 5;
int C[maxn], n;

int lowbit(int x) {return x & -x;}

int sum(int x) {
    int ret = 0;
    while(x) {
        ret += C[x]; x -= lowbit(x);
    }
    return ret;
}

void add(int x, int d) {
    while(x <= n) {
        C[x] += d; x += lowbit(x);
    }
}

int get_sum(int L, int R) {
    return sum(R) - sum(L-1);
}

int main() {
    int q, d;
    while(cin >> n >> q) {
        memset(C, 0, sizeof(C));
        for (int i = 1; i <= n; ++i) {
            cin >> d;
            add(i, d);
        }
        int qL, qR;
        while(q--) {
            cin >> qL >> qR;
            cout << get_sum(qL, qR) << endl;
        }
    }

    return 0;
}