Description
You are given an integer array nums.
A subsequence sub of nums with length x is called valid if it satisfies:
(sub[0] + sub[1]) % 2 == (sub[1] + sub[2]) % 2 == ... == (sub[x - 2] + sub[x - 1]) % 2.
Return the length of the longest valid subsequence of nums.
A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.
Example 1:
Input: nums = [1,2,3,4]
Output: 4
Explanation:
The longest valid subsequence is [1, 2, 3, 4].
Example 2:
Input: nums = [1,2,1,1,2,1,2]
Output: 6
Explanation:
The longest valid subsequence is [1, 2, 1, 2, 1, 2].
Example 3:
Input: nums = [1,3]
Output: 2
Explanation:
The longest valid subsequence is [1, 3].
Constraints:
2 <= nums.length <= 2 * 1051 <= nums[i] <= 107
Solution
Python3
class Solution:
def maximumLength(self, nums: List[int]) -> int:
N = len(nums)
c = nums[0] % 2
even = odd = both = 0
ans = 0
for i in range(N):
if nums[i] % 2 == 0:
even += 1
else:
odd += 1
if nums[i] % 2 == c:
both += 1
c = 1 - c
return max(both, even, odd)