ELI5: Linear Search
Tags: programming, computerscience, algorithms
Published: 2023-09-21 01:26:42

## Introduction

Searching is a fundamental operation in computer science and everyday life. Imagine searching for your favorite book in a library, or scanning a shopping list for a specific item at the grocery store. In the world of computer algorithms, one of the simplest and most intuitive searching techniques is the Linear Search. In this article, we'll demystify Linear Search using the ELI5 (Explain Like I'm 5) approach, making it easy for everyone to understand.

## The Hunt for the Lost Toy: Linear Search Explained

Imagine you have a row of colorful toy blocks, each with a number written on it. You've been asked to find a specific block with a particular number. How would you do it?

1. **Start from the Beginning:** You'd start at one end of the row of blocks, probably the leftmost one.
2. **Check Each Block:** Then, you'd look at each block, one by one, starting from the first one. You compare the number on the block with the number you're searching for.
3. **Find It or Continue:** If the number on the block matches, you found your toy! If not, you move on to the next block and repeat the process.
4. **Repeat Until Found:** You keep doing this until you either find the block you're looking for or you reach the end of the row and realize it's not there.

Congratulations, you've just performed a Linear Search! It's called "linear" because you're searching through the elements one by one, in a straight line, from start to finish.

## Linear Search in the World of Computers

In the computer world, we often need to find specific pieces of data in lists or arrays. Linear Search is like your search for the toy block but applied to a computer program.

Here's how it works in the context of programming:

1. **Start at the Beginning:** The computer begins at the first element of the list.
2. **Check Each Element:** It compares the value in the current position with the value it's searching for.
3. **Find It or Continue:** If it finds a match, it stops and reports the position. If not, it moves on to the next element.
4. **Repeat Until Found:** This process continues until the computer either finds the desired item or checks the entire list and concludes that the item is not there.

## Time and Space Complexity

Linear Search is simple and easy to understand, but it's not always the most efficient. Its time complexity is O(n), meaning that in the worst case, you might have to check every single element in the list. However, it's great for small lists or when you don't know if the item is near the beginning or end.

One advantage of Linear Search is its space complexity, which is O(1). It doesn't require additional memory that grows with the input size; it uses a constant amount of memory.

## When to Use Linear Search

Linear Search is handy when:
- You have a small list or array.
- You don't know the order of the elements.
- You need to find the first occurrence of an item.

However, for larger datasets or when you need to perform frequent searches, more advanced search algorithms like Binary Search are more efficient.

## Conclusion

In summary, Linear Search is like looking for a toy block one by one in a row of blocks. It's simple to understand, has a predictable time and space complexity, and is useful in specific scenarios. While it may not be the fastest search algorithm, it's an essential concept in the world of computer science and provides a solid foundation for understanding more complex searching techniques.

Next time you need to find something in a list, remember your childhood toy block search - you're essentially performing a Linear Search, one step at a time, until you locate what you're looking for.