#413 - Arithmetic Slices

Medium • View on LeetCode • View on GitHub

Problem Description

An integer array is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same.

For example, [1,3,5,7,9], [7,7,7,7], and [3,-1,-5,-9] are arithmetic sequences.

Given an integer array nums, return the number of arithmetic subarrays of nums.

A subarray is a contiguous subsequence of the array.

Solution

/**
 * @param {number[]} nums
 * @return {number}
 */
var numberOfArithmeticSlices = function(nums) {
  if (nums.length < 3) return 0;
  let result = 0;

  for (let i = 2, value = 0; i < nums.length; i++) {
    if (nums[i] - nums[i - 1] === nums[i - 1] - nums[i - 2]) {
      value++;
      result += value;
    } else {
      value = 0;
    }
  }

  return result;
};