Quick Sort Algorithm: A Quick Guide to Do It in Data Structure Assignment

Need to Know the Top Algorithms of Data Structures

Quick Sort Algorithm Guide
07 Sep 2019 3804 5 minutes

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The reason many students seek data structure assignment writing services is the failure to comprehend the algorithms. Therefore, to help you and all the others, here we are explaining quick sort which is one of the crucial algorithms. Study the next section carefully to know about it.

Quick Sort Algorithm: What It Is?

To do something it is very important to understand it first. Before going ahead with applying this algorithm, you must first have a clear understanding of what it is and its uses. You must have heard about the merge algorithm, right? Well, the quick sort algorithm is very similar to it. They both are divide and conquer algorithms. It identifies the pivot value and creates two arrays, one for the items greater than it whereas the other for the items lesser than this value.

Now a question has surely popped up in your mind that what this pivot value is, right? Well, here is the answer.

Pivot Value: It is the point of comparison. Based on this value, the data structure analysts divide the already existing list into smaller ones. After dividing the list, the following two conditions must be fulfilled:

  • Items less than the pivot value are on the left-hand side
  • Items greater than the pivot value are on the right-hand side

Now that you know what pivot means, the question arises, how to choose this value? Well, go through the next section to get the answer.

Choosing Pivot Value

Making the correct choice for pivot value is of utmost importance as this is the point based on which an unsorted list is sorted. Here are the general guidelines for choosing it:

  • The pivot can either be the first or last element of the list.
  • If you want to keep the left and right side of the list equal after sorting, then choose the middle value as the pivot.

By now you must have understood the basics of quicksort. Thus, now is the time to move towards the most awaited section.

How Quick Sort Works?

Are you excited to get acquainted with how quicksort works? We know you are. Therefore, without making you wait more, let's explain this concept with an example. Consider the following unsorted list

8, 11, 8, 2, 16, 1, 5

We will use the above-mentioned set of numbers to perceive the quick sort process. There is a series of steps for sorting the data using quick sort algorithm. Here we explain them, taking this collection of numbers as a reference.

Step 1

Choose the pivot value

As we have discussed earlier, the process of sorting data through quick sort begins with determining the pivot or central value. In our example, let’s pick 5 as the pivot value.

Step 2

Arrange the data

The next step after selecting the pivot value is arranging the data taking it as the focal point. All the values lesser than the pivot are moved towards the left side whereas the greater values are rearranged on the right side of the list. In our example, 2 and 1 are less than 5, whereas, 8, 11, and 16 are greater than 5. Thus, our data will be arranged as 1, 2, 5, 8, 16, 11.

Step 3

Choose the pivot again

Still, the list is not sorted, the next step is to choose the pivot again from both the sides of the list. In our example, let's choose 2 as the pivot from the left side as 11 from the right side. Notice that there is just a single element on the left that is lesser than the pivot, i.e., 1. This means that the left side is sorted.

Step 4

Look at both sides

Have a glance at both sides of the list to find the items that still need sorting. Here in our example, the left side is perfect but the right side has 16 which is greater than the pivot 11.

Step 5

Sort the unsorted

The last step revealed the unsorted items from both sides. In this step, you need to sort them. In our example, we have one item, i.e., 16 on the right side that needs sorting. Move it towards the right side of the pivot as it is greater than it. Now the list looks as 1,2,5,8,11,16.

Is the sorting process clear to you now? We hope, it is. But, if anything remains unclear, then we are here to help, contact us without hesitation.

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