# Merge Two Unsorted Arrays into the First Array You are given two unsorted integer arrays, `a` and `b`. The final `len(b)` positions of `a` are placeholders, so the first `len(a) - len(b)` positions contain its real values. Merge every value from `b` into `a`, sort all real values in ascending order, and leave the result in `a`. For example: ```text a = [5, 1, 3, 0, 0, 0] b = [6, 2, 4] a becomes [1, 2, 3, 4, 5, 6] ``` The task does not require constant auxiliary space; state the space used by the approach you choose. ### Constraints & Assumptions - Both real portions are unsorted. - The placeholder suffix of `a` has exactly enough positions to hold `b`. - A zero in the real prefix of `a` is data; placeholder positions are identified by their location, not their value. - The caller observes the sorted result through the mutated array `a`. ### Clarifying Questions to Ask - Is returning `a` in addition to mutating it useful for the target language's API? - May a built-in comparison sort be used? - Are there memory restrictions beyond storing the supplied arrays? ```hint Identify the real prefix by length The number of valid elements initially in `a` is `len(a) - len(b)`, regardless of the placeholder value. ``` ```hint Exploit the relaxed space requirement Because both inputs are unsorted, first filling the reserved suffix and then sorting the full array is a direct baseline. ``` ### Evaluation Criteria - Correct use of only the real prefix of `a` before copying `b` into its reserved suffix. - Ascending ordering with duplicates and negative values handled normally. - In-place mutation of the supplied destination array. - `O((m+n) log(m+n))` time for the direct sort-based approach and an accurate statement of the sorting implementation's auxiliary space. ### Extensions to Discuss - How would the solution improve if both real input portions were already sorted? - If constant auxiliary space were required while both inputs remained unsorted, what sorting strategy and trade-offs would you consider? - How would you test that a real zero in `a` is not mistaken for a placeholder?