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// @Title: 摆动序列 (Wiggle Subsequence)
// @Author: 15816537946@163.com
// @Date: 2020-12-13 19:18:24
// @Runtime: 0 ms
// @Memory: 2.1 MB

// 贪心
func wiggleMaxLength(nums []int) int {
	n := len(nums)
	if n < 2 {
		return n
	}

	ret := 1
	prevDiff := nums[1] - nums[0]
	if prevDiff != 0 {
		ret = 2
	}

	for i := 2; i < n; i++ {
		diff := nums[i] - nums[i-1]
		if diff > 0 && prevDiff < 0 || diff < 0 && prevDiff > 0 {
			ret++
			prevDiff = diff
		}
	}

	return ret
}