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 Bar Raiser's evaluation lives. Most prep treats it as a bonus question. The Bar Raiser treats it as the round. TL;DR: Amazon's Bar Raiser is an independent interviewer with veto power who tests the same problems as a regular round but probes the follow up much harder. Two things make Amazon prep different from Google or Meta prep: the pattern coverage is broader (eleven plus pattern families vs.…