题目描述

样例

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        int[] arr = new int[n + 1];//前缀和数组
        for (int i = 1; i <= n; i++) {
            arr[i] = arr[i - 1] + scanner.nextInt();
        }
        for (int i = 0; i < m; i++) {
            int l = scanner.nextInt();
            int r = scanner.nextInt();
            System.out.println(arr[r] - arr[l - 1]);
        }
    }
}

算法1

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

blablabla

算法2

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

blablabla