3201 - Find the Maximum Length of Valid Subsequence I\.

Medium

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:

• <code>2 <= nums.length <= 2 * 10⁵</code>

• <code>1 <= numsi<= 10⁷</code>