题解 | #【模板】前缀和#

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

int main() {
    int n, q;
    cin >> n >> q;
    //原数组
    vector<int> arr(n + 1);
    //前缀和数组
    vector<long long> dp(n + 1);
    //输入数组值并计算前缀和数组
    for(int i = 1; i <= n; i++)
    {
        cin >> arr[i];
        dp[i] = dp[i - 1] + arr[i];
    }
    //按q组输出
    while (q--) { 
        int l = 0, r = 0;
        cin >> l >> r;
        cout << dp[r] - dp[l - 1] << endl;
    }

    return 0;
}