Coding interviews test two things at once: whether you can solve a problem, and whether you can explain your thinking while you do it. Many strong engineers fail the second part. This plan covers both.
Step 1: Learn the patterns, not every problem
There are thousands of practice problems online, but most interview questions are built from a small set of patterns. Focus on these first:
- Arrays and strings: two pointers, sliding window, prefix sums.
- Hash maps and sets: counting, grouping, and fast lookups.
- Linked lists: fast and slow pointers, reversing a list.
- Trees: depth-first and breadth-first search, recursion.
- Graphs: BFS for shortest paths, DFS for connected parts, topological sort.
- Heaps: “top k” problems and merging sorted lists.
- Binary search: on sorted arrays and on the answer itself.
- Dynamic programming: start with simple one-dimensional problems before moving to grids.
When you solve a problem, write down which pattern it used. After a few weeks you will start to recognize the pattern from the problem statement.
Step 2: Practice like the real interview
Solving problems silently at your desk is not the same as solving them in front of someone. Make practice closer to the real thing:
- Set a timer for 30 to 40 minutes per problem.
- Talk out loud while you work, even when you are alone.
- Use a plain editor without autocomplete, since many interview platforms have limited tools.
- Do mock interviews with a friend, or record yourself and watch it back.
Step 3: Use a repeatable approach in every interview
Interviewers like candidates who stay calm and organized. Follow the same steps every time:
- Repeat the problem in your own words and ask about inputs, outputs, and limits.
- Walk through an example by hand, including one edge case.
- Describe a simple solution first, even if it is slow, and state its complexity.
- Improve it and explain why the faster version works.
- Write the code cleanly, with clear variable names.
- Test it with your example and the edge cases.
- State the final time and space complexity.
Steps 1, 2, and 7 are where many candidates lose easy points, because they skip them under pressure.
Step 4: Prepare for the follow-up questions
After you solve the problem, most interviewers ask one or two follow-ups:
- “What is the time and space complexity?”
- “How would this change if the input did not fit in memory?”
- “What edge cases did you consider?”
- “Can you make it faster?”
Have short, clear answers ready for each.
Step 5: Do not forget the other rounds
A full interview loop usually includes more than coding. Plan time for:
- System design, for mid-level and senior roles. Our system design interview guide gives you a simple structure.
- Behavioral questions, often at the end of the day. Use the STAR method to prepare.
How InterviewStorm helps in coding rounds
InterviewStorm reads a coding problem from your screen and shows the approach first, then a working solution, then the edge cases and complexity, in the same order you should explain them. That makes it useful both for practice and for live rounds where AI help is allowed. See the coding interview assistant.
A simple four-week schedule
- Week 1: arrays, strings, hash maps. Two problems a day.
- Week 2: linked lists, trees, binary search. Two problems a day, one out loud.
- Week 3: graphs, heaps, simple dynamic programming. One mock interview.
- Week 4: mixed problems under a timer, two mock interviews, and behavioral prep.
Consistency beats volume. One problem a day, done properly and explained out loud, is worth more than five rushed ones.