题解 | 【模板】前缀和

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int q = sc.nextInt();

        long[] arr = new long[n + 1];
        for (int i = 1; i <= n; i++) {
            arr[i] = sc.nextLong() + arr[i - 1];
        }

        for (int i = 0; i < q; i++) {
            int l = sc.nextInt();
            int r = sc.nextInt();
            System.out.println(arr[r] - arr[l - 1]);
        }
    }
}