题解 | #【模板】静态区间和（前缀和）#

前缀和模板。

#include<bits/stdc++.h>
#define int long long
#define double long double
#define x first
#define y second
using namespace std;
typedef long long LL;
typedef long long ll;
typedef pair<int, int> PII;
const int N = 1e6 + 10;
const int M = 1e3 + 10;
int mod = 1e9 + 7;
int a[N];

void solve() {
    int n, q;
    cin >> n >> q;
    for (int i = 1; i <= n; i++) cin >> a[i], a[i] += a[i - 1];
    while (q--) {
        int l, r;
        cin >> l >> r;
        cout << a[r] - a[l - 1] << '\n';
    }
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int _;
    _ = 1;
    //cin>>_;
    while (_--) {
        solve();
    }
}