Some Algorithms...

This week in lecture we learned about a few sorting algorithms. Three of the ones we learned are selection sort, quick sort and merge sort. I already learned about selection sort from CSC108, and I am very familiar with it. However, quick and merge sort were new to me. It’s interesting how many different ways there are to sort and produce the same product.

From what I learned in class, quick sort takes a value or pivot and uses this pivot  to divide the list into two separate lists. Basically, it compares each value to its pivot and either places each value into a greater than, or less than list. The pivot is sorted since it is placed between the two sub lists. Then, using recursion, quick sort will completely sort the list by picking new pivots until each value is in its proper place.

The merge sort algorithm is much different. It divides the list into several sub lists that contain only one element in each. Then, the algorithm gradually merges sub lists and sorts each new list. This step continues to happen recursively until there is one sorted list left. 

I can’t decide which of the two is faster and more efficient: merge or quick sort. I guess that it depends on the case. For example, if you have a large list, and for each new pivot in quick sort your algorithm happens to choose the smallest value, your quick sort will be vary slow. However, if your code selects the median value every time, your quick sort will be much more efficient. Since it chooses a value at random, the efficiency of your algorithm may vary.