Google coding interview prep
One hard problem, and they want to see how you think about it.
What the loop actually looks like
Google leans toward a single meatier problem per round, often with follow-ups that push you to generalise or optimise. Interviewers are trained to probe your reasoning, so an articulate path to a good solution frequently outweighs silently landing the perfect one.
What they reward
- Depth over speed — expect follow-ups that change the constraints
- Justifying why an approach is correct, not just that it passes
- Graphs, dynamic programming, and search-space reasoning
- Clean abstractions and naming
Patterns to drill first
Problems worth your time
In priority order. Open one to read the approach, or generate an interactive lesson and watch it run.
Word BreakA prefix is breakable if some split point is breakable and the remainder is a word.
Medium
Longest Increasing SubsequenceKeep the smallest possible tail for each subsequence length.Medium
Course ScheduleYou can finish all courses iff the prerequisite graph has no cycle.Medium
Number of IslandsEach unvisited land cell launches a flood fill that sinks its whole island.Medium
Search in Rotated Sorted ArrayAt every step, one half is still sorted — decide which, then whether the target lies in it.Medium
Koko Eating BananasBinary search the answer: eating speed is monotonic in whether she finishes in time.Medium
Coin ChangeFewest coins for amount = 1 + the best over amount minus each coin.Medium
Combination SumReuse allowed: recurse on the same index until the remaining target goes negative.Medium
Tips specific to this loop
- — Say the brute force out loud, give its complexity, then improve it — that path is the thing being graded.
- — When you get a follow-up, restate the new constraint before you start solving it.
- — Binary search on the answer shows up more than people expect. Learn to spot the monotonic predicate.
Drill these with interactive lessons
Generate a step-by-step lesson for any problem above — trace every variable and watch the pattern move until it clicks.
Start a free lessonPrepping for other companies
Our own editorial read on this loop, based on publicly reported experiences — not leaked or current question banks.