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 in = new Scanner(System.in);
        // 读入数据
        int n = in.nextInt(), q = in.nextInt();
        int[] arr = new int[n+1];
        for(int i = 1; i <= n; i++){
            arr[i] = in.nextInt();
        }
        // 预处理前缀和
        long[] dp = new long[n+1];
        for(int i = 1; i <= n; i++){
            dp[i] = dp[i-1] + arr[i];
        }
        // 输出
        while(q > 0){
            int l = in.nextInt(), r = in.nextInt();
            System.out.println(dp[r] - dp[l-1]);
            q--;
        }

    }
}