码蹄杯 背军理 题型：简单一维前缀和

码题集OJ-背军理 (matiji.net)

前缀和板子题，默写即可。

#include <bits/stdc++.h>
using namespace std;
int n;
const int N = 1e5 + 10;
int a[N], sum[N];

int main() {
	cin >> n;
	for (int i = 1; i <= n; i++)
		cin >> a[i];
	for (int i = 1; i <= n; i++)
		sum[i] = sum[i - 1] + a[i];

	int q;
	cin >> q;
	while (q--) {
		int l, r;
		cin >> l >> r;
		cout << sum[r] - sum[l - 1] << endl;
	}

	return 0;
}