Question

Formatted question description: https://leetcode.ca/all/1630.html

 1630. Arithmetic Subarrays

 A sequence of numbers is called arithmetic if it consists of at least two elements, and the difference between every two consecutive elements is the same. More formally, a sequence s is arithmetic if and only if s[i+1] - s[i] == s[1] - s[0] for all valid i.

 For example, these are arithmetic sequences:

 1, 3, 5, 7, 9
 7, 7, 7, 7
 3, -1, -5, -9

 The following sequence is not arithmetic:

 1, 1, 2, 5, 7
 You are given an array of n integers, nums, and two arrays of m integers each, l and r, representing the m range queries, where the ith query is the range [l[i], r[i]]. All the arrays are 0-indexed.

 Return a list of boolean elements answer, where answer[i] is true if the subarray nums[l[i]], nums[l[i]+1], ... , nums[r[i]] can be rearranged to form an arithmetic sequence, and false otherwise.



 Example 1:

 Input: nums = [4,6,5,9,3,7], l = [0,0,2], r = [2,3,5]
 Output: [true,false,true]
 Explanation:
 In the 0th query, the subarray is [4,6,5]. This can be rearranged as [6,5,4], which is an arithmetic sequence.
 In the 1st query, the subarray is [4,6,5,9]. This cannot be rearranged as an arithmetic sequence.
 In the 2nd query, the subarray is [5,9,3,7]. This can be rearranged as [3,5,7,9], which is an arithmetic sequence.
 Example 2:

 Input: nums = [-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10], l = [0,1,6,4,8,7], r = [4,4,9,7,9,10]
 Output: [false,true,false,false,true,true]


 Constraints:

 n == nums.length
 m == l.length
 m == r.length
 2 <= n <= 500
 1 <= m <= 500
 0 <= l[i] < r[i] < n
 -105 <= nums[i] <= 105

Algorithm

Write a function to determine whether an array is an Arithmetic array. Then construct the sub-arrays in sequence according to the requirements of the topic, and then judge.

Code

Java

    class Solution {
        public List<Boolean> checkArithmeticSubarrays(int[] nums, int[] l, int[] r) {
            int m = l.length;
            List<Boolean> res = new ArrayList<>();
            for (int i = 0; i < m; i++) {
                Boolean item = isArithmetic(Arrays.copyOfRange(nums, l[i], r[i] + 1));
                res.add(item);
            }
            return res;
        }

        public Boolean isArithmetic(int[] nums) {
            Arrays.sort(nums);
            int len = nums.length;
            int d = nums[1] - nums[0];
            for (int i = 2; i <= len - 1; i++) {
                if (nums[i] - nums[i - 1] != d) {
                    return false;
                }
            }
            return true;
        }
    }

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