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.
Example 1:
Input: nums = [1,2,3,4] Output: 3 Explanation: 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
Solution
Python3
class Solution:
def numberOfArithmeticSlices(self, nums: List[int]) -> int:
n = len(nums)
res = curr = 0
for i in range(2, n):
if nums[i] - nums[i - 1] == nums[i - 1] - nums[i - 2]:
curr += 1
res += curr
else:
curr = 0
return res