LeetCode: Arithmetic Slices Solution

1/**
2 * @param {number[]} A
3 * @return {number}
4 */
5var numberOfArithmeticSlices = function (A) {
6  const N = A.length
7  let res = 0
8  let acc = 0
9  for (let i = 2; i < N; i++) {
10    if (A[i] - A[i - 1] === A[i - 1] - A[i - 2]) {
11      acc++
12      res += acc
13    } else {
14      acc = 0
15    }
16  }
17  return res
18}
19
20var numberOfArithmeticSlices = function (A) {
21  const N = A.length
22  let res = 0
23  let acc = 0
24  for (let i = 2; i < N; i++) {
25    if (A[i] - A[i - 1] === A[i - 1] - A[i - 2]) {
26      acc++
27    } else {
28      res += (acc * (acc + 1)) / 2
29      acc = 0
30    }
31  }
32  res += (acc * (acc + 1)) / 2
33  return res
34}