代码

import java.util.*;

public class Main{
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt(), m = in.nextInt();
        int[] nums = new int[n];
        for (int i = 0; i < n; i++) nums[i] = in.nextInt();
        int sum = 0;
        int[] preSum = new int[n];
        for (int i = 0; i < n; i++) {
            sum += nums[i];
            preSum[i] = sum;
        }
        for (int i = 0; i < m; i++) {
            int left = in.nextInt(), right = in.nextInt();
            int rangeSum = left == 1 ? preSum[right - 1] : preSum[right - 1] - preSum[left - 2];
            System.out.println(rangeSum);
        }
    }
}