Arithmetic Slices

Problem statement

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.

Example 1:

Input: nums = [1,2,3,4]Output: 3Explanation: We have 3 arithmetic slices in nums: [1, 2, 3], [2, 3, 4] and [1,2,3,4] itself.

Example 2:

Input: nums = [1]Output: 0

Constraints:

• 1 <= nums.length <= 5000
• -1000 <= nums[i] <= 1000

My solution

/**
 * @param {number[]} nums
 * @return {number}
 */
var numberOfArithmeticSlices = function(nums) {
    if (nums.length <= 2) {
        return 0;
    }
    
//     let result = 0;
//     let left = 0;
//     let right = 2;
//     let diff = nums[1] - nums[0];
//     let i = 0;
    
//     while(right < nums.length) {
//         console.log(left, right, result, i)
//         if (nums[right] - nums[right - 1] === diff) {
//             right+=1;            
//             i+=1
//             result+=i;
//         } else {
//             i = 0
//             left = right - 1;
//             diff = nums[right] - nums[right - 1];
//             right+=1
//         }
//     }
    
    let result = 0;
    let count = 0;
    for (let i = 2; i < nums.length; i++) {
        if (nums[i] - nums[i - 1] === nums[i - 1] - nums[i - 2]) {
            count++
        } else {
            count = 0
        }
        
        result += count;
    }
    
    return result;
};

// if (nums[right] - nums[right - 1] === diff) {
//     right+=1;
//     i+=1;           
//     result+=i;
// } else {
//     i=0;
//     left=right-1;

//     diff=nums[right]-nums[right-1];
//     right+=1;
// }