 # Sorting in Data Structures

Amit Kumar Ghosh  12 min read
21 Sep 2023
Intermediate
414 Views

## Sorting in Data Structures: An Overview

Sorting algorithms in data structures is an important part of data structures and computer science. Knowing how sorting algorithms work can save you a great deal of time and help make your code more efficient. Whether you're just starting out with programming, or you have several years of experience under your belt, understanding the basics behind sorting algorithms will give you a leg up in designing more complex programs. In this article, we'll take a look at several common Sorting in Data Structure, sorting algorithms in data structures, Sorting in data structures with example, and sorting techniques in data structures,  used today and discuss their different characteristics and uses in detail.

## What are sorting algorithms in data structures?

Sorting algorithms in data structures refer to the methods used to arrange data in a particular order. In the world of computer science, sorting algorithms are one of the most essential topics that students need to learn. There are various sorting algorithms, such as bubble sort, quick sort, selection sort, and merge sort, all designed to perform different operations on data. Sorting algorithms can help in organizing data to make it more accessible to work with and even speed up processing times for larger amounts of data.

## Why Sorting in Data Structure is Important?

Many issues become simple when you conduct sorting on an array or items (such as min/max, kth smallest/largest). Sorting produces a number of algorithmic methods that include numerous additional concepts, including:

• Iterative
• Divide-and-conquer
• Comparison vs non-comparison based
• Recursive

## Types of sorting algorithms

### In-place Sorting and Not-in-place Sorting

Sorting is the process of arranging elements in a specific order, such as numerical, lexicographic, or alphabetical. There are two main types of sorting algorithms based on how they rearrange elements in memory: in-place sorting and not-in-place sorting.

#### In-place Sorting

• In-place sorting algorithms rearrange the elements within the array being sorted, without using any additional memory.
• In other words, the algorithm operates directly on the input array, modifying its content in place.
• Common examples of in-place sorting algorithms include: 1. Bubble Sort
2. Insertion Sort
3. Selection Sort
4. Quicksort
5. Heapsort
• One of the main advantages of in-place sorting algorithms is that they are memory-efficient, as they do not require any additional space beyond the original array.
• However, in-place sorting algorithms can be less efficient in terms of time complexity, as they often need to perform more operations to rearrange the elements within the array.

#### Not-in-place Sorting

• Not-in-place sorting algorithms, on the other hand, require additional memory to store intermediate results, often creating a new array to hold the sorted elements.
• Common examples of not-in-place sorting algorithms include: 1. Merge Sort
2. Counting Sort
• Not-in-place sorting algorithms can be more memory-intensive than in-place sorting algorithms, but they can also be more efficient in terms of time complexity, especially for large datasets.
• Additionally, not-in-place sorting algorithms can be easier to implement and understand, as they do not require complex in-place operations.

### Stable and unstable sorting algorithm

Sorting is arranging data in a specific order, typically ascending or descending order. Sorting algorithms can be classified into two categories: stable and unstable sorting algorithms.

#### Stable Sorting Algorithm

• Stable sorting algorithms maintain the relative order of elements with equal values in the original data set.
• That is if two elements have the same value, the stable sorting algorithm will sort them in the same order as they appear in the original data set.
• Stable sorting algorithms are useful in certain applications where preserving the relative order of equal elements is important.
• Some examples of stable sorting algorithms are Merge Sort, Insertion Sort, and Bubble Sort.

#### Unstable sorting algorithm

• On the other hand, unstable sorting algorithms do not guarantee the relative order of elements with equal values in the original data set.
• That is, the order in which elements with the same value appear in the sorted output may not be the same as their order in the original data set.
• Unstable sorting algorithms are often faster than stable sorting algorithms, but they may not be suitable for certain applications where preserving the relative order of equal elements is important.
• Some examples of unstable sorting algorithms are Quick Sort, Heap Sort, and Selection Sort.

In computer science, sorting algorithms are used to arrange a list of elements in a specific order. There are two main categories of sorting algorithms: adaptive and non-adaptive sorting

• An adaptive sorting algorithm is one that can change its behavior based on the input data.
• In other words, an adaptive sorting algorithm can adjust its approach to sorting depending on the characteristics of the input data.
• Examples of adaptive sorting algorithms include quicksort, insertion sort, and mergesort.
• These algorithms are adaptive because they can take advantage of the partially sorted nature of some input data to reduce the amount of work required to sort the data.
• For example, if a portion of the input data is already sorted, an adaptive sorting algorithm can skip over that portion of the data and focus on sorting the remaining elements.

• On the other hand, a non-adaptive sorting algorithm always uses the same approach to sorting, regardless of the input data.
• Examples of non-adaptive sorting algorithms include selection sort and bubble sort.
• These algorithms are non-adaptive because they do not take advantage of any partial ordering of the input data.
• They always follow the same process to sort the data, regardless of its characteristics.
• In general, adaptive sorting algorithms are faster than non-adaptive sorting algorithms for most types of input data, especially when the input data is partially ordered.
• However, in some cases, non-adaptive sorting algorithms can perform better for specific types of input data.

## Types of Sorting Algorithms in Data Structure

### Quick Sort:

Quick Sort is a divide-and-conquer method that divides an array into two sub-arrays, one with elements fewer than the pivot and one with elements more than the pivot. It operates by choosing a "pivot" element.

#### Example:

Quick Sort may decide to use 6 as the pivot and divide the array into [4, 2] and [9, 23, 12] if it is given an array with the values [4, 2, 9, 6, 23, 12]. Sort these sub-arrays iteratively.

### Bubble Sort:

Until the entire list is sorted, Bubble Sort iteratively goes through the list, compares nearby elements, and swaps them if they are out of order.

#### Example:

Bubble Sort would swap 4 and 2 first, then 9 and 6, and so on, until the list is sorted, starting with [4, 2, 9, 6, 23, 12].

### Merge Sort:

A divide-and-conquer technique known as merge sort separates the input array into smaller sub-arrays sorts them, and then combines the sorted sub-arrays to create a final array that is sorted.

#### Example:

Merge Sort splits the input [4, 2, 9, 6, 23, 12] into [4, 2, 9] and [6, 23, 12], sorts them, and then combines them to create the sorted array.

### Insertion Sort:

Insertion Sort creates the final sorted array one item at a time. Each element from the input array is taken, and it is inserted into the sorted part of the array at the proper place.

#### Example:

Insertion Sort would insert each member in the proper order, creating a sorted array, starting with an empty sorted array and [4, 2, 9, 6, 23, 12].

### Selection Sort:

Selection Sort repeatedly locates the smallest element in the array's unsorted portion and inserts it at the start. Until the full array is sorted, this is done.

#### Example:

Given the array [4, 2, 9, 6, 23, 12], Selection Sort would choose 2 as the minimum value, swap it with element 1, and keep doing so until the array is sorted.

### Heap Sort:

The input array is initially transformed into a binary heap data structure by heap sort. The greatest element from the heap, which is always at the root, is then continually removed, and the heap is rebuilt until the array is sorted.

#### Example:

Given [4, 2, 9, 6, 23, 12], Heap Sort would construct a max-heap and then iteratively remove the largest element (23, 12, 9, 6, 4, 2) to obtain the sorted array.

Integers are sorted using the non-comparative Radix Sort algorithm, which groups digits by their place value and sorts them from least to most significant.

#### Example:

Radix Sort would begin by sorting on the unit place, then the tens place, and so on, resulting in a sorted array for [170, 45, 75, 90, 802, 24, 2, 66].

### Bucket Sort:

Bucket Sort divides the input array into a defined number of buckets, distributes the items across the buckets, sorts each bucket, and then concatenates the sorted buckets to get the sorted array.

#### Example:

Bucket Sort, given [0.42, 0.25, 0.37, 0.1, 0.53], might build buckets for each decimal place and sort the components within each bucket to get the sorted array.

## Some other Sorting algorithms

• Bucket sort
• Shell sort
• Tim Sort
• Comb Sort
• Pigeonhole sorting
• Cycle Sort
• Cocktail Sort
• Strand sort
• Bitonic Sort
• Stooge Sort
• Tag Sort
• Tree sort
• Cartesian Sort
• Odd-Even Sort / Brick Sort
• 3-way Merge Sort
• Gnome sort
• Cocktail shaker sort

## Complexity of sorting algorithms

Sorting algorithms can be classified based on their time and space complexity. Time complexity is the amount of time it takes for an algorithm to execute, while space complexity is the amount of memory an algorithm requires to execute. Here are some of the most commonly used sorting algorithms and their time and space complexity:

1. Bubble Sort:
• Time Complexity: O(n^2) for the worst and average case, and O(n) for the best case (when the input is already sorted).
• Space Complexity: O(1).
2. Insertion Sort:
• Time Complexity: O(n^2) for the worst and average case, and O(n) for the best case (when the input is already sorted).
• Space Complexity: O(1).
3. Selection Sort:
• Time Complexity: O(n^2) for all cases.
• Space Complexity: O(1).
4. Merge Sort:
• Time Complexity: O(n log n) for all cases.
• Space Complexity: O(n).
5. Quick Sort:
• Time Complexity: O(n log n) for the average case, and O(n^2) for the worst case.
• Space Complexity: O(log n) for the average case, and O(n) for the worst case.
6. Heap Sort:
• Time Complexity: O(n log n) for all cases.
• Space Complexity: O(1).

Overall, while some algorithms like Bubble Sort and Selection Sort have simple implementations, they have higher time complexity, making them inefficient for larger datasets. In contrast, algorithms like Merge Sort and Quick Sort have a better time complexity, making them more efficient for larger datasets, but require more memory.

## FAQs

### 1. Which Sorting is best in Data Structure?

The optimum sorting method in data structures is determined by the context and requirements.

### 2. Which Sort is the fastest in Data Structure?

The fastest sorting method in data structures typically depends on the data and the situation, however, Quick Sort and Merge Sort are two quick possibilities.

### 3. What is Sorting in data structures with examples?

Sorting is the process of placing data elements in a certain order, such as ascending or descending. Sorting a list of numbers in ascending order, for example, [5, 2, 8, 1] results in [1, 2, 5, 8].

### 4. Why sorting is used in data structure?

Sorting is used in data structures to efficiently organize and retrieve data, making it easier to search for, insert, and analyze data.

##### Summary

In conclusion, sorting algorithms in data structures are important to review regularly. They can provide an efficient way of organizing and storing data and reduce the amount of time spent searching for information. Sorting algorithms can be complex and tricky to use correctly, so it's essential to take your time and brush up on them often. Keeping up-to-date on sorting practices also ensures maximum accuracy as well as helps you keep your skills sharp.

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