Role-ordered prep · free
DSA prep for an SDET / QA role
SDET loops are not the light coding round people expect. Candidate reports from 2024-2025 describe Amazon running 5 DSA questions in 90 minutes and Zomato opening with 3. Arrays and strings dominate: 7 core topics covering 96 of our 370 problems, with 56 of those 96 at medium difficulty. Budget real algorithm time, not a token pass.
Learn these first
Core topics for a SDET / QA loop — everything else waits until these hold.
- 1ArraysWalk through it →
- 2StringsWalk through it →
- 3Two PointersWalk through it →
- 4StackWalk through it →
- 5QueueWalk through it →
- 6RecursionWalk through it →
- 7SortingWalk through it →
Then these
Problems to start with
Named problems from this role's core topics, easiest first. Each page shows which roles treat it as core, which sheets carry it, and the companies that have asked it.
- Two Sum · Easy
- Maximum and Minimum Element in an Array · Easy
- Reverse the Array · Easy
- Contains Duplicate · Easy
- Chocolate Distribution Problem · Easy
- Best Time to Buy and Sell Stock · Easy
- Merge Sorted Arrays · Easy
- Pascal's Triangle · Easy
- Majority Element · Easy
- Sort an Array of 0s 1s and 2s · Easy
- Leaders in an Array · Easy
- Check if Array is Sorted and Rotated · Easy
What candidates actually reported
Interview reports from 4 companies, dated and linked. Read them yourself; that is the point.
- Amazon December 2024 · India“There were 5 DSA questions, focusing purely on DSA for 1.5 hours.” Questions listed as LeetCode Medium: arrays and graph traversal.
- Zomato March 2025 · India“The first round consisted of DSA questions covering topics like strings and arrays.” Three questions reported.
- Swiggy April 2025 · IndiaLeetCode problem, easy to medium. “Majorly arrays and string problems.”
- Apple May 2025 · IndiaA medium-hard Trie question that evolved into a binary search problem, plus a string-based DSA question.
What this ordering pushes down
Graphs, dynamic programming, backtracking, heaps, bit manipulation, tries, sliding window, greedy and math sit below the core tier for SDET. That is a ranking, not a guarantee: the same reports show a medium-hard Trie question at Apple and a graph traversal at Amazon. Treat the lower tier as what to reach last, not what to skip.
Why an order beats a list
Every popular sheet hands all 370 problems to everyone in the same fixed sequence. A SDET / QA interview does not weight them the same way a backend interview does — so a fixed list spends your first weeks on topics your loop barely tests. Pick this role in the app and the same problems re-sequence: core topics first, the rest after.
Questions
How much DSA does an SDET interview actually ask?
More than most people expect. Candidate reports from 2024-2025 include Amazon running 5 DSA questions across 90 minutes and Zomato opening with 3. Our ordering puts 7 core topics and 96 of 370 problems in the core tier for this role.
Which topics come up most in SDET rounds?
Arrays and strings, repeatedly. Across the candidate reports we checked, arrays appeared in 5 of 8 and strings in 4 of 8. That matches the core ordering here, which leads with arrays (34 problems) and strings (22).
Can I skip graphs and dynamic programming for SDET?
They are ranked below the core tier, not excluded. The same reports that show arrays and strings dominating also include a graph traversal at Amazon and a medium-hard Trie at Apple. Reach them last, but do not assume they cannot appear.
Is SDET prep different from SDE prep?
The problem set is the same 370; the order differs. A backend loop puts 10 topics and 260 problems in its core tier. SDET puts 7 and 96, weighted toward arrays, strings and the stack/queue family rather than graphs and DP.
Preparing for a different role?
19 more roles are available inside the app — pick yours on the Problems page.