题解 | 【模板】前缀和

#include <iostream>
using namespace std;
#include <vector>
int main() {
    int n, m;
    cin >> n >> m;
    vector<long long>s(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> s[i];
    }
    for (int i = 1; i <= n; i++) {
        s[i] = s[i - 1] + s[i];
    }
    while (m--) {
        int l, r;
        cin >> l >> r;
        cout << s[r] - s[l - 1] << endl;
    }
    return 0;
}
// 64 位输出请用 printf("%lld")