NOTE
Linear Search
Sequentially scanning elements when no useful index/order exists.
This is a historical learning note and may contain outdated or incomplete understanding.
Linear search checks elements one by one until a match is found or the input ends.
Worst-case time is O(n) and extra space is constant. Despite its simplicity, it can be appropriate for tiny collections or one-off scans where building/maintaining an index would cost more than the search itself.