I recently finished Amazon the 26NG SDE OA, and both questions passed successfully. The second question was challenging, had a strong business background, and included a long description, but I had practiced similar problems before and handled it steadily. This year's Amazon OA still had two coding questions: the first was more algorithmic, while the second was closer to a real business scenario. Below I will share the full translated questions, solution ideas, and preparation takeaways.
Question 1: Minimum Time for Drone Delivery on a Circular Route
Amazon is expanding its next-generation drone delivery network, which consists of m delivery hubs arranged in a circle, where hub 1 is adjacent to hub m. A drone can move to any adjacent hub, and the travel time between hub i and its adjacent hub is given by the array transitionTime[].
Now a series of priority delivery requests has been received. Packages must be picked up or delivered at specific hubs in the given order, represented by an array of length N called requestedHubs. The drone starts from hub 1, and your task is to calculate the minimum total travel time needed to complete all delivery requests.
NoticeUse 1-based indexing.
Example:
- m = 3
- N equals 4
- transitionTime = [3, 2, 1]
- requestedHubs = [1, 3, 3, 2]
Problem-solving ideas:
- The hubs form a circle, so you can move clockwise or counterclockwise and choose the shortest path each time.
- For each consecutive pair of requested hubs, calculate both the clockwise and counterclockwise distances and add the smaller one.
- It is recommended to precompute prefix sums so that the clockwise distance between any two points can be obtained quickly.
Question 2: Fixing the MovieDB “Follow Actor + Notification” Feature Bug
MovieDB is an application that allows users to browse movies, submit ratings, and share reviews. The “Follow Actor + Notification” feature is designed to notify users when an actor they follow has a new movie released, but the system currently has bugs.
Symptoms:
- After users follow an actor, they cannot receive notifications when a new movie is released.
- The notification count shown on the UI is incorrect, and after clicking it, users find that these “unread notifications” do not actually exist.
Reproduction steps:
- Log in with the following account:
- 邮箱：[email protected]
- Password: Password@0123
- Click the avatar on the navigation bar → select the "Follow Actors" page.
TaskLocate the root cause and fix the bug so that notifications work correctly, while also correcting the notification-count display.
Problem-solving ideas:
This is a typical full-stack bug-fixing problem that requires checking both frontend and backend code. The issue usually appears in notification generation logic, database query conditions, frontend state updates, or cache refresh. It is recommended to first map the entire notification flow from generation to display, then fix the broken points one by one.
Tips for preparing for war
- The first question is a classic variation of the shortest path on a circular structure, so practicing circular arrays and graph problems will help.
- The second question is more engineering-oriented, so it is important to become familiar with bug fixing and full-stack debugging in advance.
- Suggested time allocation: keep the first question to around 30 minutes and leave enough time for the second question.
Recommended Study Materials
If you are preparing for the Amazon 26NG / SDE Intern OA, I strongly recommend systematic practice plus targeted mock sessions. Besides official LeetCode and HackerRank practice, I personally recommend ProgramhelpTheir mentors have rich experience tutoring OA for major tech companies, especially in helping students organize Amazon high-frequency question types, AI coding, and bug-fixing questions, while providing targeted solution guidance and mock practice.
Students who need help can learn more about Programhelp services. The mentors will provide practical advice based on your specific situation.
Students preparing for Amazon 26NG are welcome to share your OA experiences in the comments.
I wish everyone passes the OA soon and gets an Amazon offer!
