# 3392. Count Subarrays of Length Three With a Condition """ given an integer array 'nums', return the number of subarrays of length 3 such that the sum of the first and third number equals exactly half of the second number. """ class Solution(object): def countSubarrays(self, nums): """ :type nums: List[int] :rtype: int """ return sum(l + r << 1 == m for l, m, r in zip(nums, nums[1:], nums[2:])) if __name__ == "__main__": obj = Solution() print(obj.countSubarrays(nums=[1, 2, 1, 4, 1])) print(obj.countSubarrays(nums=[1, 1, 1]))