Section 13: Ten Suggestions, Eight Times a Search - Final Summary & Candidate Scorecard

Executive Summary: This closing section turns the module into a way to grade yourself. We replay the interview arc and name the signal each phase was recording, then lay out a 100-point scorecard across six dimensions. The largest weight goes to deep-dive depth, because "a trie" is where every candidate starts and how far past it they get is what separates Staff from Senior. Score bands map to readiness levels, and a final catalogue shows where this question hides in real loops.

Almost every candidate says "trie" in the first two minutes, and almost every candidate is right. That word earns very few points. The interviewer was listening for what came after it: one search becomes eight requests, the edge absorbs most of a million requests a second, the whole index fits in one machine's memory so you replicate it, and a suggestion is the platform speaking, so some must never appear.

The Arc, Replayed as Signal

Read the right-hand column as the interviewer's notebook.

Key Insight: Not one signal is "knows Lucene" or "can code a trie." Each is about moving work out of the keystroke path: into the client, the CDN, a nightly build, a precomputed top-K list. The serving path stays read-only and boring, and that is the design.

Quick check before moving on: