2170\. Minimum Operations to Make the Array Alternating

Medium

You are given a **0-indexed** array `nums` consisting of `n` positive integers.

The array `nums` is called **alternating** if:

*   `nums[i - 2] == nums[i]`, where `2 <= i <= n - 1`.
*   `nums[i - 1] != nums[i]`, where `1 <= i <= n - 1`.

In one **operation**, you can choose an index `i` and **change** `nums[i]` into **any** positive integer.

Return _the **minimum number of operations** required to make the array alternating_.

**Example 1:**

**Input:** nums = [3,1,3,2,4,3]

**Output:** 3

**Explanation:**

One way to make the array alternating is by converting it to [3,1,3,**1**,**3**,**1**].

The number of operations required in this case is 3.

It can be proven that it is not possible to make the array alternating in less than 3 operations. 

**Example 2:**

**Input:** nums = [1,2,2,2,2]

**Output:** 2

**Explanation:**

One way to make the array alternating is by converting it to [1,2,**1**,2,**1**].

The number of operations required in this case is 2.

Note that the array cannot be converted to [**2**,2,2,2,2] because in this case nums[0] == nums[1] which violates the conditions of an alternating array. 

**Constraints:**

*   <code>1 <= nums.length <= 10<sup>5</sup></code>
*   <code>1 <= nums[i] <= 10<sup>5</sup></code>