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#1630 - Arithmetic Subarrays
Problem Description
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.
Solution
/**
* @param {number[]} nums
* @param {number[]} l
* @param {number[]} r
* @return {boolean[]}
*/
var checkArithmeticSubarrays = function(nums, l, r) {
return l.map((start, index) => {
const end = r[index];
const subarray = nums.slice(start, end + 1);
return isArithmetic(subarray);
});
function isArithmetic(subarray) {
if (subarray.length < 2) return false;
subarray.sort((a, b) => a - b);
const diff = subarray[1] - subarray[0];
for (let i = 2; i < subarray.length; i++) {
if (subarray[i] - subarray[i - 1] !== diff) return false;
}
return true;
}
};