# Time: O(n) # Space: O(1) # array class Solution(object): def alternatingSubarray(self, nums): """ :type nums: List[int] :rtype: int """ result = l = -1 for i in xrange(len(nums)-1): if l != -1 and nums[i-1] == nums[i+1]: l += 1 else: l = 2 if nums[i+1]-nums[i] == 1 else -1 result = max(result, l) return result