Py3 C++奇偶交錯奇偶子數列解Leecode 3201 Find the Maximum Length of Valid Subsequ...

Py3  C++奇偶交錯奇偶子數列解Leecode 3201  Find the Maximum Length of Valid Subsequence I

求最長有效子序列，使得 (sub[0] + sub[1]) % 2 == (sub[1] + sub[2]) % 2 == ... == (sub[x - 2] + sub[x - 1]) % 2，有 3 種可能的情況

-全為偶數

-全為奇數

-或奇偶交錯子序列

[Py3解請進]

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To find the longest valid subsequence such that (sub[0] + sub[1]) % 2 == (sub[1] + sub[2]) % 2 == ... == (sub[x - 2] + sub[x - 1]) % 2, it has 3 possible cases

- all evens

- all odds

- or alternative subsequence

[codes on Leetcode]https://leetcode.com/problems/find-the-maximum-length-of-valid-subsequence-i/solutions/6964221/even-odd-or-alternative-beats-100/

class Solution:
    def maximumLength(self, nums: List[int]) -> int:
        n=len(nums)
        if n==2: return 2
        z=nums[0]&1
        Len=[1-z, z, 1]
        for xx in nums[1:]:
            x=xx&1
            Len[x&1]+=1
            if x!=z:
                Len[2]+=1
                z=1-z
        return max(Len)