If you are also preparing for a DS internship position in North America and are particularly interested in data infrastructure / data science / ML infra positions, the Walmart (retailer) Labs The interview process of the company is worth to know seriously. It is quite friendly to new graduates, and the overall process is relatively clear, the pace does not drag, is a lot of students in the heart of the "data direction of the first choice to practice".
One of the students we recently assisted successfully completed Walmart DS Intern The following is based on the actual assistance process, restore the whole process, for your reference.
Overview of the interview process (with OA)
| point | formality | Summary of contents |
|---|---|---|
| Online Assessment OA | Modern Hire + HackerRank | Modern Hire behavioral questions + HackerRank two algorithmic questions (Python + SQL) |
| First round of technicals | Zoom Remote | Python code-based, with a focus on practical programming skills |
| Second round of technicals | Zoom Remote | Two SQL questions on self join + GREATEST/LEAST + date boundaries |
| Third round of technicals | Zoom Remote | Multiple rounds of coding + analysis for logic clarity, code robustness |
| Fourth round of technicals | Zoom Remote | Open-ended project-based discussion, simulating real business scenarios for modeling and evaluation |
Technical: Coding + Practical Analysis
The DS technical side of Walmartlabs is actually quite biased towards real work, although the topics are not difficult to understand, but it is very much about your proficiency in data pipeline, SQL logic, and your ability to talk about the program, it is not the kind of scenario that you can win by applying the LeetCode template.
Our student was assisted by Programhelp. We went over the technical side several times, and there were some "easy to miss pitfalls" in each round, so here they are.
Round 1: SQL + Python Hands-on Programming
This round felt like a combination of "data cleansing + preliminary analysis", where the interviewer gave you a product table and a user behavior table, and asked you about the retention of a certain product mix by quarter.
Students start out with a INNER JOIN + GROUP BY Doing the aggregation, the logic was written quickly, but neglected to filter conditions on dates -- and the interviewer followed up with, "How do you make sure you're only looking at active users in the current quarter?" That's where it got stuck for a couple minutes.
We emphasized in the mock that this kind of retention SQL should pay special attention to the granularity of the grouping + the control of the date window. That's why we prepared the date window with the WEEK()/QUARTER() of template logic, and directly able to switch ideas on the day.
The Python section is actually pretty routine, with questions like dict Processing, string preprocessing, that kind of thing, the hard part is that you have to quickly write clean logic that explains why you're doing it -- we build a clean function architecture ahead of time, and he just fills in the logic and doesn't have to improvise a function structure in a panic.
Round 2: Minimum Possible Value of Function
At first glance, this question appears to be a purely mathematical formula, but it is actually a median optimization type of problem after transformation.
The stem of the question is to give you an array X[i], define a function F(k) = sum(|X[i] - (k + i)|)The first step is to find the k that minimizes F(k).
Many people (including this student at first) get confused by the position of k, thinking that they have to violently iterate through each k to try it. In fact, as we talked about when we mocked, this type of function actually translates to a A[i] = X[i] - i, and then just take the median and sum it up.
We organized the general solution to the question "Absolute value and minimum value = median" in advance, and practiced the transformation logic repeatedly during the mock. As soon as this kind of question came up in the interview, he thought of constructing the A[i], the whole process was very smooth.
Round 3: Longest Good Subsequence
This is one of those questions that looks easy, but can't be written correctly if you're a little sloppy. A "good subsequence" is defined as one that is even in length, has the same characters in the first half, and the same characters in the second half. For example aabb, xxxxzzzz It all counts.
Our students just saw the question, the first reaction is to use the double pointer to find a subsequence that meets the conditions, but the result is that when they write it, they find that the state maintenance is too chaotic, and they get themselves confused.
Actually the optimal practice is:
- Count the frequency of each character;
- Exhausts two characters a, b, and spells them out as
aaaa + bbbbof combinations to calculate the maximum length.
When we mocked this question, we predicted that it might be a "frequency construction + optimal combination" type of question, and we gave a template for solving character frequency related questions in advance. On the day of the interview, although he thought it was complicated at first, he quickly went back to the solution we talked about before, and it ended smoothly.
wrap-up
Walmart's technical interview is frankly "do you know how to do data work or not", it's not the kind of interview where you can just apply a template and get it over with. Especially for the mixed SQL and Python questions, you need to have a whole set of logic in your head. Our student wasn't particularly skilled at first, but after 2 rounds of Programhelp's mock practice, he was able to get the rhythm and expression down, and he did quite well on the day.
FAQ: Summary of Frequently Asked Questions
| concern | solution (a math equation) |
|---|---|
| Is OA difficult? | Moderately difficult, algorithmic questions are practical, and can be easily handled with modern Python proficiency. |
| Do I need to memorize templates for SQL questions? | You don't need to memorize it, but you should be familiar with the join / group by / window function combination scenario |
| Will business modeling be difficult? | Bias towards open-ended questions, it is recommended to talk about them in the context of project experience, avoiding generalizations. |
| Is the interviewer's style relaxed? | Overall relaxed atmosphere, focusing on communication skills and code ideas, especially logic when explaining reasons |
| Is it suitable for ng students? | Great fit, walmart is friendly to new grads and is a great springboard for practicing for the DS position! |
Programhelp Help you on your way to the DS interview!
The student we assisted had remote, untethered online support from Programhelp throughout the entire interview process, including:
OA real-time collaborative ghostwriting, algorithmic questions submitted without trace
Interviews with Zoom simulations + strategies for common follow-up questions
SQL Scenario Question Template Explanation + Adaptive Expression Framework Overview
Structured response sorting (STAR method, MECE framework)
At Programhelp, we don't just brush up on questions, but use real interview contexts to help you grasp every key speaking point and break through each round of interviews efficiently and strategically.
