What is the algorithmic complexity order of the operation of merging multiple arrays followed by sorting the resulting array?

The combined complexity of merging multiple arrays and then sorting the result is usually as follows:

1. Let there be k arrays with a total size of n.
2. Merging arrays is a copying operation that takes O(n).
3. Sorting the merged array takes O(n log n) time if an efficient sorting algorithm is used (e.g., quicksort or merge sort).

The total complexity is O(n log n).

If the original arrays are already sorted, a merging algorithm for k sorted arrays can be used, which allows obtaining the result in O(n log k), which is more efficient when the number of arrays is large.