In programming, multiple sorting algorithms are used to sort elements of an array or any other data structure. This is because sorting elements makes processes more efficient and easier.

Sorting things may seem easier but in reality, things are more complex than they seem to be. Therefore, multiple sorting algorithms are used depending on the complexity of the given data structure.

But before getting into any complex methods, let’s begin with a basic sorting algorithm.

**Bubble sort** is one of the simplest and basic sorting algorithms which compares an element to its adjacent elements and then switches their locations if necessary.

But the question is how does this actually work? To understand that, keep reading this post. Here is everything you need to know about bubble sort in detail.

**What Does Bubble Sort Mean?**

The **bubble sort** algorithm is also called the sinking algorithm. The algorithm simply scans through the complete list, compares the elements to their neighbors and then switches their locations if necessary.

The same process is repeated until you receive a complete sorted list. Because the algorithm treats the uppermost elements like bubbles, the algorithm is named **bubble sort**.

It sorts the whole given list by just comparing all the elements and then sorting them in descending and ascending order.

Now, most of you must be wondering where this sorting algorithm is used. Let’s check out some applications of the **bubble sort **algorithm.

**How Is Bubble Sort Used?**

Let’s be honest, being one of the simplest sorting algorithms, it becomes a bit difficult to implement the **bubble sort** algorithm in the real world. However, it is used by a lot of programmers to understand and get hold of sorting concepts.

Here, let’s go through the ways programmers use **bubble sort**.

**To Learn Sorting**

For beginners, learning complex sorting algorithms is not that easy. Therefore, because of the easy and simple algorithm of bubble sort, it is better for a beginner to learn bubble sort first and learn how sorting works.

**To Sort Smaller Data Sets**

Bubble sort may take up a lot of time when it comes to sorting larger data sets. Therefore, it is used to sort smaller data sets by programmers.

**To Sort Sorted Data Sets**

Sometimes, programmers may also use **bubble sort **to assure that the given data structure is already sorted. The data structure that they think requires no sorting or little sorting, they prefer using bubble sort.

**How Does Bubble Sort Work?**

Well, till now we have talked about what is bubble sort and how it is used. Now, here we are going to discuss how the algorithm works.

To understand in a better way, consider the following example:

The following array is your input:

**12, 30, 24, 36, 9**

**First Iteration:**

Now when you run the first iteration, it will first compare 12 with 30. 12 is smaller than 30 and therefore, these elements are in sorted order. So, no swapping is done here.

Next, it will compare 30 with 24. Now, 30 is greater than 24 and hence, the elements require sorting. In this case, the swapping of elements is done.

After this, 30 will be compared with 36. These elements need no sorting. So, the positions of the elements will remain the same.

At the end of the first iteration, 36 and 9 will be compared. Here, elements require sorting. Therefore, the positions will be switched.

Now, on completion of this iteration, the original array will be

**12, 24, 30, 9, 36**

**Second Iteration:**

Now, in the second iteration, the same process will be followed. Here, after comparing all the elements and sorting those elements, the array will be **10, 24, 9, 30, 35.**

**Third Iteration**

After this, at the time of the third iteration, the same process is repeated and the array is sorted. After this, the sorted array will be **12, 9, 24, 30, 36**

**Fourth Iteration**

Again the array will be sorted and compared in the fourth iteration. The array will be **9, 12, 24, 30, 36**.

With this example, you may have understood how **bubble sort** compares each element and then swap locations.

However, one thing that you need to observe is that here the data set was small. What if you need to sort a larger data set? In that case, other sorting algorithms are preferred.

**Complexity Analysis Of Bubble Sort**

Understanding the space and time complexity of an algorithm is of utmost importance before implementing an algorithm. Below we have discussed the time and space complexity of **bubble sort**.

**Space Complexity**

In all cases, the space complexity of bubble sort remains constant. Because the algorithm uses an additional space, the complexity is calculated as O(1).

**Time Complexity**

The time complexity of bubble sort is different in different scenarios. Here, let’s discuss the average, worst and best case time complexity of** bubble sort**.

**Best Case:**Here, the complexity is calculated as O(n). This is the case when the given list is sorted.**Average case:**This complexity is calculated as O(n/2 *n)= O(n2). In this case, n/2 and O(n) passes are required to sort the array.**Worst Case:**Here the complexity is calculated as O(n*n)= O(n*n) O(n2). In this case, the algorithm requires n passes to sort an array. Here, n is the size of the list.

**Bonus Topic **

**How to find the longest palindromic substring in java?**

Different paths can take you to your goal for this problem. There are three different approaches you can follow to find the longest palindromic substring. Let’s discuss these methods in detail.

**Approach 1: Brute force method**

**Idea:** The idea of this approach is to find out the substrings and check each substring individually. In this approach, each substring is checked through loops. You will have to run three different nested loops to find out the substrings and check if it’s a palindrome.

**How does it work?**

The following steps show how the algorithm of this approach works:

- First of all, accept a string as an input from the user
- Now, run three different nested loops.
- The first loop will fix the first element of the substring.
- The second loop will search through the string and find the consecutive characters of this substring.
- Once the substring is formed, the third loop will check the substring for the condition- palindrome or not.
- Since these nested loops will work till the end of this string, each substring will be checked for the given conditions.
- Once you check it, you can return the longest substring among the palindromic substring.

Print this substring as an output for the user and your problem will be solved.

**Approach 2: Dynamic programming**

**Idea**: The idea of this approach is similar to brute force yet with reduced time complexity. In this method, the memorization of data is used to reduce the overall execution time of the code. In this approach, a substring already checked and added with certain characters will be considered a palindrome only.

**Conclusion**

So, this was all about the **bubble sort **algorithm. Though it is a basic sorting algorithm, it still holds a significant place in the lives of programmers.

To your surprise, this sorting algorithm has been asked about in many interviews along with crucial questions like how to** print longest palindromic subsequence** or how to find the subsequence of a string.

However, always remember that** bubble sort** is not an ideal approach to sort large data sets and has minimal real-life implementation. But learning the same is important as it is one of the most important building blocks of programming.

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