<p>You are given an integer array <code>nums</code>. The <em>value</em> of this array is defined as the sum of <code>|nums[i] - nums[i + 1]|</code> for all <code>0 &lt;= i &lt; nums.length - 1</code>.</p>

<p>You are allowed to select any subarray of the given array and reverse it. You can perform this operation <strong>only once</strong>.</p>

<p>Find maximum possible value of the final array.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,3,1,5,4]
<strong>Output:</strong> 10
<b>Explanation: </b>By reversing the subarray [3,1,5] the array becomes [2,5,1,3,4] whose value is 10.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [2,4,9,24,2,1,10]
<strong>Output:</strong> 68
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>2 &lt;= nums.length &lt;= 3 * 10<sup>4</sup></code></li>
	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
	<li>The answer is guaranteed to fit in a 32-bit integer.</li>
</ul>

class Solution:
    def maxValueAfterReverse(self, nums):
        total_diff = 0
        min_value = float('inf')
        max_value = float('-inf')

        for index in range(len(nums) - 1):
            current = nums[index]
            next_value = nums[index + 1]
            total_diff += abs(current - next_value)
            min_value = min(min_value, max(current, next_value))
            max_value = max(max_value, min(current, next_value))

        additional_diff = max(0, (max_value - min_value) * 2)

        for index in range(len(nums) - 1):
            current = nums[index]
            next_value = nums[index + 1]
            head_contribution = -abs(current - next_value) + abs(nums[0] - next_value)
            tail_contribution = -abs(current - next_value) + abs(nums[-1] - current)
            additional_diff = max(additional_diff, max(head_contribution, tail_contribution))

        return total_diff + additional_diff

21000