Quick sort and merge sort algorithms

Question

Elucidate quick sort and merge sort algorithms?

Answer 1

Quick sort uses the ‘conquer and divide’ concept by dividing list of elements in two sub elements
The process is illustrated below:

1. Pick an element, pivot, from list.

2. Rearrange elements in list, so that all elements those are less than the pivot are arranged before pivot and all elements those are greater than the pivot are arranged after pivot. Now the pivot is in it position.

3. Sort the both sub lists – sub list of the elements that are less than the pivot and the list of elements that are more than the pivot recursively.

Merge Sort: A comparison based sorting algorithm. The input order is preserved in sorted output.

Merge Sort algorithm is illustrated below:

1. The length of list is 0 or 1, and then it is considered as sorted.

2. Otherwise, divide unsorted list in 2 lists each about half the size.

3. Sort each sub list recursively. Implement the step 2 till the two sub lists are sorted.

4. as a final step, combine (merge) both the lists back in one sorted list.