376. Wiggle Subsequence.go

package leetcode

func wiggleMaxLength(nums []int) int {
	if len(nums) < 2 {
		return len(nums)
	}
	res := 1
	prevDiff := nums[1] - nums[0]
	if prevDiff != 0 {
		res = 2
	}
	for i := 2; i < len(nums); i++ {
		diff := nums[i] - nums[i-1]
		if diff > 0 && prevDiff <= 0 || diff < 0 && prevDiff >= 0 {
			res++
			prevDiff = diff
		}
	}
	return res
}