Implement `merge_sorted_unique(sorted_arrays)`. Each input array is sorted in ascending order. Merge all arrays into one ascending array containing each value exactly once. Empty arrays and values repeated within or across arrays must be handled correctly. Let `N` be the total number of input elements and `k` the number of arrays. Target `O(N log k)` time and `O(k)` auxiliary space, excluding the returned array. ```hint Keep one frontier value per array Put the first value from every nonempty array into a min-heap together with its array and position. ``` ```hint Deduplicate at the output boundary After removing the next smallest value, append it only when it differs from the last emitted value, then advance within the same source array. ``` ### Discussion Extensions - For exactly three arrays, compare a three-pointer implementation with the heap-based general solution. - How would the algorithm change if the inputs were streams rather than materialized arrays?