Longest Common Prefix
Recognize the pattern
Brute force idea
The naive version of Longest Common Prefix sounds like this: Compare every string against every other. That direct path helps you understand the question, but it tends to treat every possibility as brand new instead of learning from earlier steps.
Better approach
The real unlock in Longest Common Prefix comes when you notice this: Compare characters column by column across all strings — where m is shortest string. Instead of recomputing the world every time, you preserve just enough context to let the next decision become obvious.
Key invariant
The compass for Longest Common Prefix is this: The prefix can only be as long as the shortest string. As long as that statement keeps holding, you can trust the steps built on top of it.
Watch out for
The trap in Longest Common Prefix usually looks like this: Not handling the empty array case or single-string case. When the code becomes mechanical before the idea is clear, small edge cases start breaking the whole story.