Find shortest subarray with range ≥ k

## Problem You are given an integer array `nums` of length `n` and an integer `k`. Define the **range** of a subarray as: \[ \max(\text{subarray}) - \min(\text{subarray}) \] Return the **length of the shortest non-empty contiguous subarray** whose range is **at least** `k`. If no such subarray exists, return `-1`. ## Input - `nums`: array of integers (can include negatives) - `k`: non-negative integer ## Output - An integer: the minimum length of a qualifying subarray, or `-1` if none exists. ## Constraints (typical interview scale) - `1 <= n <= 2 * 10^5` - `-10^9 <= nums[i] <= 10^9` - `0 <= k <= 10^9` ## Examples - `nums = [1, 3, 2], k = 2` → answer `2` (subarray `[1,3]` has range `2`) - `nums = [5, 5, 5], k = 1` → answer `-1`