0. How FAANG Interviews Work

The Format

A typical FAANG coding interview is 45–60 minutes, structured roughly as:

 5 min  — Introductions, clarifying the problem
15 min  — Discussing approach / brute force → optimised
20 min  — Coding the solution
10 min  — Testing, edge cases, complexity analysis
 5 min  — Your questions for the interviewer

You'll usually solve 1–2 problems on a shared editor (no IDE, no autocomplete).

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What Interviewers Actually Evaluate

FAANG interviewers score on four axes — not just correctness:

Axis	What they look for
Problem solving	Can you break it down? Brute force first, then optimise
Communication	Do you think aloud? Explain decisions before coding
Coding	Clean, readable code; handles edge cases
Verification	Do you test with examples? Trace through your code?

A correct solution with zero communication scores lower than a nearly-correct solution with excellent reasoning.

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The Think-Aloud Framework

Use this structure for every problem:

1. UNDERSTAND
   - Restate the problem in your own words
   - Ask clarifying questions (input types? null? empty? duplicates? sorted?)
   - Work through 1–2 examples by hand

2. BRUTE FORCE
   - State the naive solution first ("I could do this in O(n²) by...")
   - Analyse its complexity

3. OPTIMISE
   - Identify the bottleneck ("The nested loop is the issue...")
   - Think about what data structure would help
   - State the pattern ("This looks like a sliding window / two pointer / DP problem")

4. CODE
   - Write clean code, naming variables clearly
   - Explain each non-obvious line as you write it

5. TEST
   - Walk through your code with the given example
   - Test edge cases: empty input, single element, all same values, negatives
   - State time and space complexity

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Signal Words → Patterns

Memorise this table. Hearing a signal word should immediately suggest a pattern.

Signal word / phrase	Think about
"sorted array", "pair that sums to"	Two pointers
"subarray", "substring", "contiguous", "window"	Sliding window
"k closest", "top k", "kth largest"	Heap
"prefix", "range sum", "count subarrays"	Prefix sum / hash map
"tree", "hierarchy", "parent-child"	DFS / BFS
"shortest path", "minimum steps", "level by level"	BFS
"all paths", "all combinations", "generate all"	Backtracking (DFS)
"minimum/maximum cost to reach", "number of ways"	Dynamic programming
"sorted", "find position", "rotated array"	Binary search
"unique", "count occurrences", "group by"	Hash map / set
"connected components", "union", "merge groups"	Union-Find
"prefix matching", "autocomplete"	Trie

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