Recently, many classmates have been meeting Pinterest OA, the overall style is obvious: it is no longer just the traditional LeetCode, but a mixed examination of "algorithm + data science foundation + implementation ability". I have completely organized this set of questions for you, including the core ideas and keys to solving the questions. It is suitable for temporary cramming or system review.
OA overall situation
- Platform:HackerRank
- Question volume: Generally 3-4 questions (slightly different in different batches)
- Duration:90-120 minutes
- Features: The first half is about partial algorithm implementation, and in the second half, machine learning hand-picked questions (Bagging, k-Means, etc.) begin to appear, which require higher coding capabilities and ML basics.
The following are 6 exclusive real questions that have appeared frequently recently and detailed solutions:
Pinterest OA question bank exposed | Exclusively compiled by Programhelp
Question 1: Local Maxima Indices
Problem description
Given an integer array rawData and an integer localArea, find the subscripts of all local maxima in the array and return them in ascending order.
Local maximum definition:
- Strictly decreasing localArea elements starting from i and going to the right; or
- Starting at i and going strictly leftward to the beginning of the array.
Example:
RawData = [2, 10, 4, 3, 11, 5, 2, 6, 12, 3, 2], localArea = 2
Output: [1, 8]
Problem-solving ideas:
- Traverse each position i
- Check whether the right side satisfies the strictly decreasing localArea length
- Checks whether all elements on the left are strictly less than the current value
- Collect all subscripts that meet the conditions and sort them
Question 2: Maximum value of matrix expression
Problem description
Given a matrix containing only numbers, +, -, starting from any number cell, you can only move all the way to the right or all the way down to form a legal expression and find the maximum value among all possible expressions.
Rule:
- Operators cannot appear consecutively
- Numbers cannot appear consecutively
- Must start with a number
Problem-solving ideas:
- DFS traverses all legal paths
- Maintain the value of the current expression and the previous character type as you go
- Pay attention to the handling of negative signs
Topic 3: Minimum height difference of mountain peaks
Problem description
Given the peak height array heights and the minimum viewing distance viewingGap, find the minimum height difference between all pairs of peaks that satisfy |i – j| >= viewingGap.
Example:
Heights = [1, 5, 4, 10, 9], viewingGap = 3
Output: 4
Problem-solving ideas:
- Violent O(n²) prone to timeout
- It is recommended to use sorting + double pointer or sliding window + monotonic stack optimization
Topic 5: Bagging algorithm implementation
Core requirements:
- Implementing a Bagging classifier from scratch (without using sklearn)
- Self-service sampling (Bootstrap)
- Train multiple base classifiers
- A majority vote determines the final result (a tie vote selects the lower numbered class)
Key points: Implemented strictly according to the sampling method required by the question.
Topic 6: k-Means clustering implementation
Core requirements:
- Implement k-Means algorithm from scratch
- Iterate the specified number of times
- Returns the cluster number for each data point
Implementation points:
- Calculate Euclidean distance
- Update centroid mean
- Pay attention to empty cluster processing and numerical stability
Some practical advice
If you are already in the sprint stage, you will actually find a problem:
OA such as Pinterest is rarely about "stuck ideas", but more about stuck time + card implementation details + card boundaries. Many students know how to do it, but they just can't get through it in time, or they fail because of a corner case.
This is why many people now use auxiliary platforms like Programhelp to provide the last layer of protection.
They mainly do several things:
- OA real-time assistance(Supports HackerRank / Codesignal and other platforms)
- Voice reminder for programming stuck points (the kind that won’t interrupt your train of thought)
- VO / Real-time tips for interviews (strategy + idea guidance)
- Compilation of high-frequency question bank (many of which are "just passed")
The more critical point is:
They prefer "low-interference assistance" rather than rough proxying, which is actually very important in today's increasingly strict monitoring environment.
Of course, whether you need assistance depends on your own preparation. But if you have reached the bottleneck, or just missed the mark, this method can really help you reduce "uncertainty".
