1630. Arithmetic Subarrays

QUESTION:

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
-10^5 <= nums[i] <= 10^5

EXPLANATION:

其实只要模拟这样的过程就可以了
1.截取l到r的数组进行排序
2.算出步长
3.循环截取数组查看步长是否一致
4.将步长结果放到result中

SOLUTION:

class Solution {
    func checkArithmeticSubarrays(_ nums: [Int], _ l: [Int], _ r: [Int]) -> [Bool] {
        var result:[Bool] = []
        for indexRange in l.indices {
            var tmpArr = nums[l[indexRange]...r[indexRange]].sorted()
            let differenct = tmpArr[1] - tmpArr[0]
            var differenceEqual:Bool = true
            for index in 0..<tmpArr.count-1 {
                if (tmpArr[index+1]-tmpArr[index] != differenct) {
                    differenceEqual = false
                    break
                }
            }
            result.append(differenceEqual)
        }
        return result

    }
}
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