Merge Sorted Array

You are given two integer arrays `nums1` and `nums2`, sorted in **non-decreasing order**, and two integers `m` and `n`, representing the number of elements in `nums1` and `nums2` respectively. **Merge** `nums1` and `nums2` into a single array sorted in **non-decreasing order**. The final sorted array should not be returned by the function, but instead be _stored inside the array _`nums1`. To accommodate this, `nums1` has a length of `m + n`, where the first `m` elements denote the elements that should be merged, and the last `n` elements are set to `0` and should be ignored. `nums2` has a length of `n`.   **Example 1:** **Input:** nums1 = [1,2,3,0,0,0], m = 3, nums2 = [2,5,6], n = 3 **Output:** [1,2,2,3,5,6] **Explanation:** The arrays we are merging are [1,2,3] and [2,5,6]. The result of the merge is [1,2,2,3,5,6] with the underlined elements coming from nums1. ``` **Example 2:** **Input:** nums1 = [1], m = 1, nums2 = [], n = 0 **Output:** [1] **Explanation:** The arrays we are merging are [1] and []. The result of the merge is [1]. ``` **Example 3:** **Input:** nums1 = [0], m = 0, nums2 = [1], n = 1 **Output:** [1] **Explanation:** The arrays we are merging are [] and [1]. The result of the merge is [1]. Note that because m = 0, there are no elements in nums1. The 0 is only there to ensure the merge result can fit in nums1. ```   **Constraints:** - `nums1.length == m + n` - `nums2.length == n` - `0 <= m, n <= 200` - `1 <= m + n <= 200` - `-109 <= nums1[i], nums2[j] <= 109`   **Follow up: **Can you come up with an algorithm that runs in `O(m + n)` time?