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Beginner Topic 6 of 51 Algorithms

Linear Search

Scanning elements one by one until a match is found.

How it works

Linear search scans a collection from the first element to the last, comparing each item with the target until it finds a match or reaches the end. It needs no ordering and no extra memory, and takes O(n) time in the worst and average cases, with O(1) best case when the target is first. Sentinel techniques can reduce comparisons slightly.

Where it is used

Looking up an item in a small or unsorted list, searching linked lists where random access is impossible, finding the first element matching a condition and one-off lookups where sorting would cost more all use linear search.

Common pitfall

Using it repeatedly on large data is slow; build a hash table or sort and use binary search. Forgetting to handle not found, or returning an index of zero that is read as false, causes bugs. Stop at the first match if only one is needed.

Where it fits in the course

Linear Search is topic 6 of 51 in Algorithms, rated Beginner. It follows Big-O Notation. The next topic is Binary Search.

Practice and explore

How to study this topic

  1. Read the explanation above and restate the definition in your own words.
  2. Open the interactive lesson and answer its mini quiz.
  3. Read the common pitfall, then write a short example that avoids it.
  4. Check your understanding in the Algorithms quiz, and revisit the topic if you miss a question.

Frequently asked questions

What is Linear Search?
Scanning elements one by one until a match is found. It belongs to Algorithms and is a beginner-level topic.
Where do people use Linear Search?
Looking up an item in a small or unsorted list, searching linked lists where random access is impossible, finding the first element matching a condition and one-off lookups where sorting would cost more all use linear search.
What is the most common mistake with Linear Search?
Using it repeatedly on large data is slow; build a hash table or sort and use binary search.
What should I learn before this topic?
Start with Big-O Notation, the topic just before it in Algorithms.
How can I practice it?
Answer the mini quiz in the interactive lesson, then take the Algorithms quiz. You can also explore Linear vs Binary Search in the Visual Lab.
Is Linear Search hard to learn?
It is a Beginner topic, so it works as an entry point. If the terms are new, read the explanation twice and try the visualizer before the quiz.
How long does it take to learn Linear Search?
Most learners can read the explanation and finish the interactive lesson in under an hour. Fluency comes from applying the idea, so plan a few short practice sessions with the quiz.
Which topics are related to Linear Search?
Big-O Notation, Binary Search, Space Complexity are closely connected. The full list is in the related topics section of this page.
What should I study after Linear Search?
Continue with Binary Search, the next topic in Algorithms.

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