The Amazon Bar Raiser Isn't Testing Your Solution. It's Testing the Follow Up.

You're 15 minutes into an Amazon coding round. You've identified the pattern, your solution handles the examples, you're about to submit. Then the interviewer changes a constraint. Sorted input is now unsorted. The complexity ceiling drops from O(n log n) to O(n) . Your original solution collapses, and the rest of the round is now about whether you can reconstruct the approach from the invariant rather than from memory. That moment, the constraint shift after the working solution, is where the B