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Lesson 3 — Linear search
Linear search: check every item
Linear search looks at items one by one until it finds the target (the value you are looking for). If it reaches the end, the target is not there, and by convention we return −1. enumerate(nums) gives you both the index (position, starting at 0) and the value.
for i, n in enumerate([5, 8]):
print(i, n) # 0 5, then 1 8
It is simple, works on any list (sorted or not), and takes up to n steps for n items — we say it is O(n), "grows in step with the list size".
Why it matters: it is the baseline every faster search is compared against.
Want it another way?
Task
Inside the loop, return i when n equals target. Expected: 2, then -1.
Run your code — when the output matches the task, you will see a green check. Then mark the lesson complete.
Test your knowledge
Test your knowledgeA quick 3-question quiz on this lesson — instant feedback.