I recently completed Square Point's Online Assessment and passed it smoothly. Below is a detailed sharing of the real questions and solution ideas for those preparing for Square Point, Jane Street, SIG, or other quant/fintech companies.
OA Overview
- Platform: HackerRank
- Duration: 75 minutes
- Questions: 2 Coding Problems
- Characteristics: Business-oriented simulation and data processing, focusing on heap usage and state maintenance. Time is relatively sufficient if managed well.
Question 1: Maximize Sales Revenue
Problem Description
Given an array of product quantities, in each step you can sell the product with the current highest quantity. After selling, reduce its quantity by 1 (if still greater than 0, it remains available for future sales). Calculate the maximum total revenue, where the revenue for each sale equals the quantity sold at that moment.
Solution Idea
- Put all quantities into a max-heap (Priority Queue) to always retrieve the largest quantity.
- Each time, take the largest quantity and add it to the total revenue.
- Decrease the quantity by 1 and push it back into the heap if it is still greater than 0.
- Repeat until the heap becomes empty.
Core Concept: Greedy + Max Heap. Always sell the currently most abundant product.
Question 2: Message Delivery with Cooldown
Problem Description
Given a sequence of messages with timestamps and a cooldown time k.
For the same message, if the interval between two deliveries is less than k, reject the current delivery.
Otherwise, allow it.
Update the last delivery timestamp regardless of whether the message is accepted or rejected.
Solution Idea
- Use a HashMap to record the last delivery timestamp for each message.
- For each incoming message:
- If the message has not appeared before, allow delivery.
- If
current_time - last_timestamp ≥ k, allow delivery. - Otherwise, reject delivery.
- Update the last timestamp in both accepted and rejected cases.
Core Concept: HashMap state maintenance + timestamp difference checking.
Preparation Tips
- Square Point OA heavily favors business simulation problems.
- Practice Heap (Priority Queue) and HashMap state-maintenance questions extensively.
- Write clean code with meaningful variable names.
- Pay attention to edge cases such as empty arrays,
k = 0, duplicate messages, and large inputs. - Recommended time allocation:
- Question 1: 20–25 minutes
- Question 2: 30–35 minutes
- Remaining time: debugging and verification
Final Thoughts
This Square Point OA reinforced an important lesson: clear logical thinking and effective time management are often more important than solving extremely difficult algorithmic problems.
Later, through a friend's recommendation, I discovered Interview Aid. Their latest question bank and solution discussions helped me quickly understand high-frequency topics and significantly improve my preparation efficiency.
If you're also preparing for Square Point, Jane Street, SIG, or other quantitative trading companies, I highly recommend spending extra time on heap-based simulations and state-management problems.
Best of luck with your preparation and hope you land your dream offer!
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