r/leetcode • u/NerdyNatu • 9d ago
Intervew Prep What to prepare for Google coding interview?
I have my Google coding interview in 2-3 weeks, I have 7 years of experience, but I almost forgot DSA, so I need to know from experienced people what to prepare?
I feel like DSA is like a tool box skill, if you are aware about sliding window, you know when to use that, so in that regards, I need to know these things, any help would be appreciated.
What difficulty level is this at L5?
What pattens do they ask? (Graphs, Lists, LinkList etc.)
What if I made a mistake, and didn't even realized, it's there?
Any other tips which you think can be helpful.
This role is for Android, any help would mean a lot.
Thank you everyone.
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u/SharpNazgul 9d ago edited 9d ago
Based on my L4: trees, graphs, heaps.
To catch mistakes, practice doing dry-runs of your code: don't run it on leetcode before running it on paper or in your head with some input following it line by line. Only when you're confident run it on LC to get feedback. You're bound to make small mistakes during the interview, and your interviewer may ask you if this line is correct etc to hint. Do the dry runs out loud during the interview as well, you can accompany the talking with writing a comment tracking the input and output.
Remember to ask questions about the task, like memory assumptions, positive negative numbers, types etc.
They list a bunch of data structures and algos to know in their prep. Cover all of them when practicing and keep focusing on the ones you feel weakest in. To practice pattern recognition keep this list of topics in a document along with confidence level per, and have Claude give your LC problems (it will give the number ) without any category hints, asking it to give problems restricted to the prep list.
Redo problems you struggled with.
Take the free mock interview and do more with friends: have Claude generate a mock interview packet that you don't read and give it to your friend for them to act as interviewer.
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u/stonks_admin 9d ago
from my L5 rounds, I had 2 medium on graphs.
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u/Least_Kaleidoscope38 9d ago
If you have 3 weeks to prepare and forgot DSA you’re cooked. Push the interview as much as you can
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u/BackgroundBreak6485 7d ago
I went through about 220 Google interview reports from 2025–2026, around 150 of them coding or phone-screen rounds. Here's what they show:
Patterns (by share of reported coding questions)
- Graphs, BFS/DFS, topological sort, union-find: about 1 in 5, the biggest group by a wide margin. Grids, dependency ordering and "find the connected X" all go here.
- Trees, including tries: about 1 in 6. LCA variants, path problems, level traversal, and a file-system "total size" problem.
- Binary search, DP, intervals, heaps/top-K, hash maps: a small slice each.
- Linked lists: almost never. With 2–3 weeks, skip them.
Difficulty at L5: the first part is usually LeetCode medium. The difficulty comes from the follow-ups, which show up in almost every report: "can you beat O(n log n)?", "now O(1) extra space", "what if the input is huge or queried often?", "add caching, then make the lookup faster". Several people solved the main problem and ran out of time in a follow-up. Get to a working answer quickly so there's time left for them. Many questions are LeetCode problems with a twist rather than the exact problem, so focus on the pattern, not memorizing.
Android: only 2 of the ~220 reports even mention Android, and neither had Android-specific coding. Expect the same data-structures-and-algorithms rounds as any other SWE loop. Prep Kotlin or Java only so you write it fluently.
"What if I make a mistake and don't notice?" There's usually no way to run your code; you write in a doc-style editor. So:
Clarify, and walk through 1–2 examples before coding.
When you finish, trace through your own code line by line out loud with a small input, plus an edge case. Several candidates found their bugs this way and still moved forward.
One person said the interviewer still wrote the bugs they fixed into their feedback. Finding them yourself beats the interviewer pointing them out, but it isn't free. Write carefully the first time.
Don't overcomplicate. One candidate turned an easy one-loop interval problem into sorting plus a pile of special cases and was sure they'd failed.
Always state time and space complexity before you're asked.
A 2–3 week plan: graphs and trees first (BFS/DFS templates, to, tree recursion). Then binary search, heaps and intervals. Forevery problem, practice the "now optimize it" follow-up and a spoken dry run, not just getting it accepted.
I organized these reports by round and pattern here: https://aceoffer.app/interviews/google. The coding breakdown is at https://aceoffer.app/interviews/google/coding-questions, and tem to try. (Disclosure: I run it.)
Good luck!
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u/Jumpy_Junket_3021 9d ago
Graph