# Comparing Heap and Selection Sorting Algorithms

Published on Wednesday, October 9, 2024

Imagine you’re building an app and need to sort a massive list of data – maybe product prices, customer names, or high scores. Choosing the right sorting algorithm can make a huge difference in performance. Today, we’ll pit two popular contenders against each other: **heap** and **selection**.

Before we dive into the code, let’s briefly explore the basics of both algorithms. If you’re eager to see the action, feel free to jump straight to the code comparison here.

*Heap* Sort

**Heap Sort** is a powerful sorting algorithm that’s often used in various applications due to its efficiency and in-place nature.

### A Brief History

Heap sort was first described in 1964 by J. W. J. Williams. However, Robert W. Floyd quickly improved upon Williams’ algorithm in the same year, making it possible to sort the array in-place without requiring extra memory.

### How It Works

Heap sort works by first building a max heap from the input array. A max heap is a complete binary tree where the value of each node is greater than or equal to the values of its children. Once the heap is built, the largest element is at the root.

**Build Max Heap:**Create a max heap from the input array.**Extract Maximum:**Swap the root element (largest element) with the last element of the heap.**Heapify:**Restore the max heap property by calling the heapify function on the root node.**Repeat:**Repeat steps 2 and 3 until the entire array is sorted.

### Time Complexity

The time complexity of heap sort is $O(n \log n)$ in both the average and worst-case scenarios. This makes it a very efficient sorting algorithm for large datasets.

### Advantages and Disadvantages

**Advantages:**

- Efficient for large datasets
- In-place sorting, requiring minimal extra memory
- Can be used for priority queues

**Disadvantages:**

- Can be slightly slower than quicksort in the average case
- May not be as stable as other sorting algorithms

### When to Use Heap Sort

Heap sort is a good choice for:

**Large datasets:**Its $O(n \log n)$ time complexity makes it suitable for sorting large arrays.**Priority queues:**Heap sort can be used to implement priority queues efficiently.**Applications where space efficiency is important:**Heap sort is an in-place algorithm, requiring minimal extra memory.

**In conclusion,** heap sort is a powerful and efficient sorting algorithm that’s widely used in various applications. Understanding its principles and advantages can help you make informed decisions when choosing a sorting algorithm for your specific needs.

*Selection* Sort

**Selection Sort** is a straightforward sorting algorithm that works by repeatedly finding the minimum element in the unsorted portion of the array and swapping it with the first unsorted element.

### How It Works

**Find Minimum:**Find the index of the smallest element in the unsorted portion of the array.**Swap:**Swap the smallest element with the first unsorted element.**Repeat:**Repeat steps 1 and 2 until the entire array is sorted.

### Time Complexity

The time complexity of selection sort is $O(n^2)$ in all cases. This means it’s not very efficient for large datasets.

### Advantages and Disadvantages

**Advantages:**

- Simple to understand and implement
- In-place sorting (doesn’t require extra memory)

**Disadvantages:**

- Inefficient for large datasets
- Not as efficient as other sorting algorithms

### When to Use Selection Sort

Selection sort is a good choice for:

**Small datasets:**When the number of elements is small, its inefficiency may not be a significant issue.**Educational purposes:**It’s a simple algorithm that’s easy to learn and understand.

**In conclusion,** selection sort is a basic sorting algorithm that’s suitable for small datasets or educational purposes. However, for larger datasets, more efficient algorithms like quicksort, merge sort, or heap sort are generally preferred.

## The Clash

We put both algorithms to the test with a battlefield of 3500 random numbers. Now, let’s see who emerges victorious!

Now that we have some data to test on, we want to add the algorithm for the **heap sort**. This goes as follows.

And of course the **selection sort** as well, otherwise we won’t have anything to compare against.

Now, let’s test the two against one another.

### Delve deeper:

For even more sorting options, explore our collection of sorting algorithms. Want to get your hands dirty with the code? Head over to **heap sort VS. selection sort Implementation**.

## The Winner

Brace yourselves! The benchmark revealed that the **heap sort** is a staggering **211.29x** faster than its competitor! That translates to running the heap sort almost 212 times in the time it takes the selection sort to complete once!

### The A.I. Nicknames the Winners:

We consulted a top-notch AI to give our champion a superhero nickname. From this day forward, the **heap sort** shall be known as ** The Heap Hero**! The selection sort, while valiant, deserves recognition too. We present to you,

**!**

*The Selection Slamme*### The Choice is Yours, Young Padawan

So, does this mean the heap sort is the undisputed king of all sorting algorithms? Not necessarily. Different algorithms have their own strengths and weaknesses. But understanding their efficiency (which you can learn more about in the Big-O Notation post) helps you choose the best tool for the job!

This vast world of sorting algorithms holds countless possibilities. Who knows, maybe you’ll discover the next champion with lightning speed or memory-saving magic!

This showdown hopefully shed light on the contrasting speeds of *heap* and *selection* sorting algorithms. Stay tuned for more algorithm explorations on the blog.