12. EDEXCEL GCSE (1CP2) Merge sort

Which of the following best describes the Merge Sort algorithm?

• It repeatedly swaps adjacent elements if they are in the wrong order.

• It works by repeatedly splitting a data set into smaller sub-problems and then combining their sorted solutions.

• It selects a 'pivot' element and partitions the array around the pivot.

• It builds the final sorted array one item at a time by repeatedly taking the next element from the unsorted input and inserting it into the correct position in the sorted array.

What is the initial step in the Merge Sort algorithm when sorting a data set?

• Comparing the first two items in the list.

• Splitting the data set into individual lists, each containing one item.

• Selecting a pivot element.

• Merging adjacent lists together.

When merging two adjacent lists in Merge Sort, how are items compared and moved to the new merged list?

• The last item of the first list is compared with the last item of the second list.

• Items are compared from the middle of each list.

• The first available item from each list is compared, and the smaller one is moved to the new merged list.

• All items from the first list are moved, then all items from the second list.

What happens if one of the lists being merged runs out of items before the other?

• The sorting process stops, indicating an error.

• The remaining items from the non-empty list are discarded.

• The remaining items from the non-empty list are safely moved over to the new merged list.

• The algorithm restarts the merging process from the beginning.

How does a merge sort algorithm primarily work?

• By comparing adjacent items and swapping them if they are out of order.

• By repeatedly splitting lists into single items and then merging them back in sorted order.

• By selecting the smallest item and placing it at the beginning of the list.

• By inserting each item into its correct position in a sorted sublist.

Which statement accurately compares Merge sort and Bubble sort regarding speed and suitability for item numbers?

• Merge sort is slow, while Bubble sort is quick.

• Merge sort is suitable for a small number of items, while Bubble sort is suitable for a large number of items.

• Merge sort is quick and suitable for a large number of items, while Bubble sort is slow and suitable for a small number of items.

• Both Merge sort and Bubble sort are equally quick for any number of items.

What is a key difference between Merge sort and Bubble sort regarding programming difficulty and memory footprint?

• Merge sort is easy to program and has a known memory footprint.

• Bubble sort is more difficult to program and its memory footprint can increase.

• Merge sort is more difficult to program and its memory footprint can increase, while Bubble sort is easy to program and has a known memory footprint.

• Both algorithms are equally difficult to program and have similar memory footprints.