HackerRank OA: what to expect and how to practise in a week

Most HackerRank OAs run for 60 to 90 minutes and mix two or three question formats in a single test window. The recruiter picks the sections from HackerRank’s question library, so no two companies feel identical, but the shape is predictable.

• Coding tasks in the language of your choice (Python, Java, C++, JavaScript, Go and others). Each task has hidden test cases; your score is the fraction that pass, not simply pass or fail.
• SQL questions against a small schema, usually 2 to 4 queries scored on exact result-set match.
• MCQs on data structures, OS, DBMS or the company’s stack.
• Functional or approximate problems where several partial-credit outputs are accepted.

The timer is per test, not per question, so you can revisit. The IDE saves as you type, but a browser crash mid-answer is not unheard of — copy your final solution to a scratch pad before you submit.

HackerRank logs a focus-out event every time you leave the test tab. It does not automatically end your test, but the recruiter sees a count in your report. A single accidental switch rarely matters; a dozen looks like copying. If webcam proctoring is enabled you will be prompted at the start; declining ends the attempt.

Copy-paste into the code editor is allowed unless the recruiter disables it. Even when allowed, pasting an entire solution from an external tab is the fastest way to trigger a plagiarism flag, because HackerRank compares your submission against a large corpus of public solutions.

Public LeetCode problems and HackerRank OA problems overlap, but the flavour is different. Recruiters pick from HackerRank’s interview preparation kit and their private question bank. Expect:

• Arrays and strings with a twist — sliding window, prefix sums, two pointers.
• Hash-map counting problems dressed up as a business scenario.
• One graph or tree traversal, usually BFS or a straightforward DFS.
• A greedy or sorting problem where the brute force times out on the largest hidden case.
• SQL joins with a group-by and a window function.

Very rarely do Indian service-company OAs include a hard dynamic programming problem in the first round. Product companies do, but usually as the second coding task with looser expectations of a full solution.

HackerRank does not publish universal cut-offs — every hiring team sets its own. In practice, candidates who clear the round typically hit two thirds of the total points or better, with at least one coding task solving all hidden cases. Service companies weight completion; product companies weight full-mark solutions on the harder task even if the easier one is only partial.

Do not chase 100 percent on question one if it means never opening question three. Read every question in the first three minutes and rank them by expected return on time.

Assume you have work or classes and can spare 90 to 120 minutes a day.

• Day 1: take one full mock at the exact length of your real test. Note where time drained.
• Day 2-3: drill arrays, strings and hash-maps. One easy, one medium a day, timed.
• Day 4: SQL — joins, group-by, window functions. Write ten queries against a sample schema.
• Day 5: one graph or tree problem plus one greedy. Focus on reading input cleanly.
• Day 6: second full mock. Compare to Day 1 for pacing.
• Day 7: revise your own past errors only. Do not learn anything new the day before.

Our free aptitude and coding practice widget below draws from a 20,000-question bank tagged by company and platform, so you can filter to HackerRank-style tasks specifically.