HRT OA Latest Interview Experience | High Frequency Questions + Tips for Passing the Exam

This time, we would like to share that our trainees participated in the HRT Quant Intern OA real experience. The entire test was conducted on the CodeSignal platform, with a total duration of 150 minutes and a total of 3 questions.The DDL is very lenient and can be completed within a month, but for insurance purposes, the students were able to get it in one go with our untraceable on-line assistance.

Q1. Base Digit Dynamic Programming

Description of the original topic:
"You are given a positive integer N. A number is called 'fancy' if its base-4 representation contains only Return the number of fancy positive integers that are strictly smaller than N."

Exam point analysis:

• Essentially a digit DP (Digit Dynamic Programming).
• Restriction: Only 0/1 can be used as a quadratic bit number.
• Requirement: Calculate all < N The fancy number counts.

Key points:

1. classifier for objects with a handle N Convert to quad to get the array digits[].
2. Design DP Status (pos, tight, started):
   • pos: The currently processed quaternary bit.
   • tight: whether it is still equal to the prefix of N .
   • started: Whether to start constructing non-zero numbers to avoid counting zeros in the result.
3. Each person can only select 0 Or 1. If tight == TrueThe selection must not exceed digits[pos].
4. After the traversal is complete, if started == True, counts as an answer.

Q2. 2048-like Grid Simulation

Description of the original topic:
"You are given a 4×4 grid and a string representing a sequence of move instructions (U, D, L, R). Each move slides all characters in the given direction. When two identical characters collide, they merge into a new character according to the rules. Output the final state of the grid after processing all moves."

Exam point analysis:

• quintessentially simulation-basedthat is more difficult to implement than the algorithm itself.
• The point is. Consolidation rules:
  • Same character collision → Generates a new character.
  • Each element can only be merged once in a move.
• The move order is executed strictly according to the command string.

Realization points:

1. Write a compress_line() function handles single row/single column:
   • Remove the spaces first to get the list.
   • Iteration checks if the neighbors are the same, and if they are, merge them and skip the next one.
   • Fill in the blanks at the end.
2. The four directions of movement can be unified by transposing/inverting the array with the compress_line().
3. Each instruction is executed once to update the board until the string runs out.

Q3. Non-Binary Tree Parsing & Merging

Description of the original topic:
Level 1.
"You are given a custom string representation of a non-binary tree. Construct the tree and implement a preorder traversal function to print its nodes."

Level 2.
*"Now, given two non-binary trees, merge them into one according to the following rules.

• If both nodes exist, merge their values using the provided rule (e.g., sum).
• If only one node exists, use that node as-is.
• Children are merged positionally (first child with first child, and so on).
  Return the merged tree and its preorder traversal. "*

Exam point analysis:

• Tree construction: You need to write parser to parse the string into Node + children[].
• (math.) ergodic: Standard preorder (root, then children).
• tree merger: Recursively process two nodes:
  • Simultaneous → merge values, recursively merge children.
  • Only one exists → Use directly.
  • Children vary in number → missing complements None.

Learner Experience Summary

The difficulty level of this set of OA is not low, and the three questions cover DP, simulation, and complex data structures, which requires a high level of code robustness and detail handling. With the on-line assistance of Programhelp, students avoided common pitfalls and ensured reasonable time allocation, and finally got all three ACs in one go.

• Q1 digit DP: leading zero error is avoided.
• Q2 simulation: avoid double merge bug.
• Q3 tree merge: avoids reference pollution.

Submission results in all green and successful completion of HRT OA.

HRT OA - Frequently Asked Questions

Q1: Is HRT's OA full of algorithmic questions?
A1: Not exactly. They're on the codesignal platform, but they're more of a comprehensive survey, involving DP, BFS, simulation, mathematical logic, and other types of questions, and the boundary conditions are often tricky.

Q2: Is it enough to brush up on the questions at regular intervals?
A2: Brushing questions can lay the foundation, but the biggest challenge in practice is time and details. Many people have the right idea of the topic, but in the last few test cases, they still fail, and the difference is not even a fraction of a mile.

Q3: What should I do if I suddenly get stuck in OA or VO?
A3: This is a situation that many people encounter. In fact, many students will look for experienced people to run with them remotely, reminding the logic in time at key points and helping you to block out the bugs, so as not to waste time.

Q4: Are there any preparation methods to improve efficiency?
A4: It is recommended to simulate the real world, not just brush up on the questions alone. For example, timing questions, training boundary conditions in advance, and having someone else help you pick out problems are all more efficient than going it alone.

Interview preparation is no longer a solo endeavor, and it's easy to break through the big factory barrier

In quant OA like HRT, not only is the question type large, but it is also easy to fall into some boundary conditions and implementation details. Many people have the right idea, but in the end, they still lose points because of small bugs. The advantage of our team is to help you get around all these potholes:

Full on-line without traces: The backend is a stable escort to ensure that all test cases pass at once.

Real-time voice assistance: Nod to key ideas right away when you hit a stuck point, no more dead ends.

safe and reliable: The operation process is completely seamless, so you can hand in your papers without worrying.

If you are also rushing quant / algo post OA and don't want to get brushed off because of details, look for the Programhelp Just right. Almost all of the students who have worked with us have passed the test in one sitting and got the opportunity easily.

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