题目
class Solution: def wiggleMaxLength(self, nums: List[int]) -> int: n = len(nums) if n < 2: return n pre = nums[1] - nums[0] res = 1 if pre == 0 else 2 for i in range(2, n): dif = nums[i] - nums[i - 1] if (dif > 0 and pre <= 0) or (dif < 0 and pre >= 0): res += 1 pre = dif return res
解题思路
贪心，如果能构成交替的序列就加上这个数，如果后面的数更小（或者更打）就替换之前的数（写的时候并不需要替换，只需要记录正负号）
代码
class Solution:
def wiggleMaxLength(self, nums: List[int]) -> int:
n = len(nums)
if n < 2:
return n
pre = nums[1] - nums[0]
res = 1 if pre == 0 else 2
for i in range(2, n):
dif = nums[i] - nums[i - 1]
if (dif > 0 and pre <= 0) or (dif < 0 and pre >= 0):
res += 1
pre = dif
return res
