Merge Two Sorted Arrays

With extra output storage, keep pointers i and j at the starts of the two sorted arrays. Repeatedly append the smaller current value, advancing that pointer, then append the unconsumed suffix when one array finishes. The invariant is that the output contains the smallest available values in sorted order. If stability matters, take from the first array on ties. This is O(m+n) time and O(m+n) output space. If the common interview variant requires merging into two existing arrays without an extra buffer, clarify whether it permits a combined temporary array or expects the gap method. The gap method compares elements gap positions apart across the conceptual concatenation, swapping when out of order, then shrinks the gap until one; it is in-place but less direct. Test empty arrays, all values from one side, duplicate values, negatives, and arrays of unequal lengths. Do not overwrite unread values in the destination.