Linear Search Algorithm
Linear Search scans elements sequentially one-by-one from the start of an array to the end until the target item is found or the array ends.
Linear Search Execution Trace
Check Index 0
Compare arr[0] (14) with target 42. 14 != 42 -> Move to next index.
arr[0] = 14 != 42 -> Increment index to 1Check Index 1
Compare arr[1] (28) with target 42. 28 != 42 -> Move to next index.
arr[1] = 28 != 42 -> Increment index to 2Target Match at Index 2
Compare arr[2] (42) with target 42. 42 == 42 -> Target found!
arr[2] = 42 == 42 -> Return Index 2Real-world analogy: Searching Lost Keys
Looking for keys in a messy drawer by checking every single pocket one by one from top to bottom.
- Sequential= Checks elements in exact linear order.
Complexity analysis
500 steps (Linear)
O(N) Linear Time
O(1) / O(N) Space
Memory growth rate as N expands.
Relative efficiency rating for large N.
| Operation | Time Complexity | Space Complexity |
|---|---|---|
| Best Case (First Item) | O(1) | O(1) |
| Average Case | O(N) | O(1) |
| Worst Case (Last / Absent) | O(N) | O(1) |
Code implementations
function linearSearch(arr, target) {
for (let i = 0; i < arr.length; i++) {
if (arr[i] === target) return i;
}
return -1;
}Real-world applications
Unsorted Lists
Scans raw unsorted user input streams.
Small Datasets
Extremely fast for small arrays under 15 elements due to CPU cache locality.
Interview questions
Topic Knowledge Test & Assessment
Linear Search Knowledge & Skill Test
Validate your conceptual understanding, operation mechanics, and core concepts of Linear Search.
Topic Metadata
Linear search requires zero preprocessing or sorting, making it ideal for single-use searches over small unsorted arrays!