题解

#include <bits/stdc++.h>
using namespace std;
int main() {
    int n ,m ,l ,r;
    cin >> n >> m;
    int lst[n + 1] = {};
    for (int i = 1 ; i <= n ; i++)
        cin >> lst[i];
    long long prefix_sum[n + 1] = {};  //前缀和列表
    for (int i = 1 ; i <= n ; i++)
        prefix_sum[i] = prefix_sum[i - 1] + lst[i];
    for (int i = 1 ; i <= m ; i++){
        int sum = 0;
        cin >> l >> r;
        cout << prefix_sum[r] - prefix_sum[l - 1] << "\n";  //输出
    }
    return 0;
}