Merge two sorted arrays in-place

You are given two sorted integer arrays `nums1` and `nums2`. - `nums1` has length `m + n`. The first `m` elements contain the sorted data in non-decreasing order. The last `n` elements are placeholders (for example, zeros) and should be ignored. - `nums2` has length `n` and contains `n` sorted elements in non-decreasing order. Merge `nums2` into `nums1` so that `nums1` becomes a single sorted array of length `m + n`, still in non-decreasing order. You must perform the merge **in-place** in `nums1`, using only O(1) additional space. Describe your algorithm in detail and analyze its time and space complexity. You do not need to provide actual code.