<p>You are given a <strong>0-indexed</strong> array <code>nums</code> of integers.</p> <p>A triplet of indices <code>(i, j, k)</code> is a <strong>mountain</strong> if:</p> <ul> <li><code>i < j < k</code></li> <li><code>nums[i] < nums[j]</code> and <code>nums[k] < nums[j]</code></li> </ul> <p>Return <em>the <strong>minimum possible sum</strong> of a mountain triplet of</em> <code>nums</code>. <em>If no such triplet exists, return</em> <code>-1</code>.</p> <p> </p> <p><strong class="example">Example 1:</strong></p> <pre> <strong>Input:</strong> nums = [8,6,1,5,3] <strong>Output:</strong> 9 <strong>Explanation:</strong> Triplet (2, 3, 4) is a mountain triplet of sum 9 since: - 2 < 3 < 4 - nums[2] < nums[3] and nums[4] < nums[3] And the sum of this triplet is nums[2] + nums[3] + nums[4] = 9. It can be shown that there are no mountain triplets with a sum of less than 9. </pre> <p><strong class="example">Example 2:</strong></p> <pre> <strong>Input:</strong> nums = [5,4,8,7,10,2] <strong>Output:</strong> 13 <strong>Explanation:</strong> Triplet (1, 3, 5) is a mountain triplet of sum 13 since: - 1 < 3 < 5 - nums[1] < nums[3] and nums[5] < nums[3] And the sum of this triplet is nums[1] + nums[3] + nums[5] = 13. It can be shown that there are no mountain triplets with a sum of less than 13. </pre> <p><strong class="example">Example 3:</strong></p> <pre> <strong>Input:</strong> nums = [6,5,4,3,4,5] <strong>Output:</strong> -1 <strong>Explanation:</strong> It can be shown that there are no mountain triplets in nums. </pre> <p> </p> <p><strong>Constraints:</strong></p> <ul> <li><code>3 <= nums.length <= 50</code></li> <li><code>1 <= nums[i] <= 50</code></li> </ul>