Time:O(n) Space:O(1) C++ class Solution { public: int wiggleMaxLength(vector<int>& nums) { int increasing = 1; int decreasing = 1; for (int i = 1; i < nums.size(); ++i) if (nums[i] > nums[i - 1]) increasing = decreasing + 1; else if (nums[i] < nums[i - 1]) decreasing = increasing + 1; return max(increasing, decreasing); } }; JAVA class Solution { public int wiggleMaxLength(int[] nums) { int increasing = 1; int decreasing = 1; for (int i = 1; i < nums.length; ++i) if (nums[i] > nums[i - 1]) increasing = decreasing + 1; else if (nums[i] < nums[i - 1]) decreasing = increasing + 1; return Math.max(increasing, decreasing); } }