题解 | #【模板】前缀和# 动态规划

#include <iostream>
#include <vector>
using namespace std;

int main() 
{    
    int n, q; cin >> n >> q;
    vector<int> arr1(n);  //n个整数
    for(int i = 0; i < n; ++i)
        cin >> arr1[i];

    //记录前n项和的数组
    vector<long long> arr2(n + 1, 0);
    for(int i = 0; i < n; ++i)
        arr2[i + 1] = arr2[i] + arr1[i];

    while(q--)
    {
        int l,r;
        cin >> l >> r;
        cout << arr2[r] - arr2[l - 1] << endl;
    }

    return 0;
}