public class Solution {
    public int wiggleMaxLength(int[] nums) {
        if (nums == null || nums.length < 1) return 0;
        int high = 1;
        int low = 1;
        int len = nums.length;
        for (int i = 1; i < len; i++) {
            if (nums[i] > nums[i - 1]) high = low + 1;
            else if (nums[i] < nums[i - 1]) low = high + 1;
        }
        return Math.max(high, low);

    }
}