Walmart Sparkplug Interview Experience For SDE Internship (2025)

I recently participated in the Walmart Sparkplug Summer Internship 2025 selection process, which took place in the 3rd and 4th week of October 2024. The process consisted of three rounds, each testing different aspects of computer science fundamentals and problem-solving skills from which the top 100 folks get a chance to be a summer intern for 2 months in the firm. All the rounds were held on Unstop.

Below are my detailed experience and insights for future aspirants.

Round 1: MCQ Challenge (Eliminatory Round)

The first round comprised 25 multiple-choice questions (MCQs), each with a strict time limit of 1 minute. The questions covered core CS subjects, including Object-Oriented Programming (OOPs), Operating Systems (OS), Database Management Systems (DBMS), and Code snippets in C and C++.

I started the round confidently. For some questions, especially the ones based on OOPs and DBMS, I took only 10-15 seconds. However, for complex problems, particularly code output-based questions, I took around 50-55 seconds. Overall, I managed to answer all the questions before time ran out.

Results were announced two days later, and I was among the 2,500 students shortlisted out of 20,000 registrations for the next round.

Round 2: Coding Challenge

The second round consisted of 2 DSA-based coding problems to be solved within 90 minutes. Due to some unforeseen circumstances, I started the test late and had only 60 minutes instead of 90. Despite the time crunch, I was able to solve both problems within 45 minutes.

Question 1: Package Distribution (Graph - Medium Difficulty)

Problem Statement: Given N houses, each house had a delivery cost. Some houses were connected, and if a package was delivered to one house, all connected houses received it. The goal was to distribute packages to all houses at the minimum cost.

My Approach: I recognized this as a graph problem where connected houses formed components. I used Disjoint Set Union (DSU) to group connected houses. For each group, I iterated among all the houses present in it selected the one with the minimum delivery cost, and summed up the costs across all groups. Since N was 10⁵, I figured out a Linear solution using DSU.

Question 2: Articulation Points (Graph - Hard Difficulty)

Problem Statement: Given an undirected connected graph, find all articulation points—removing these points disconnects the graph.

My Approach: A brute-force approach (removing each node and checking connectivity) would be inefficient. Instead, I implemented Tarjan’s Algorithm, which finds articulation points in O(V + E) time complexity. Since V was 10⁸, this approach worked out in linear time.

After a few days, results were announced, and I was among the 1,500 students shortlisted for the final round.

Round 3: Coding Challenge (Final Round)

The final round was another 90-minute coding test consisting of 2 DSA problems.

Question 1: Pattern Search in a Grid (Graph & Recursion - Easy-Medium Difficulty)

Problem Statement: Given an N × M grid with characters ('E', 'F', 'W', 'A'), find the maximum occurrences of the pattern "EFWA". Movement was allowed in four directions. Cells could not be revisited, and the path could start from any cell.

My Approach: Given the low constraints, I used Recursion + DFS to search for the pattern efficiently.

Question 2: Number Queries on Divisors (Number Theory - Hard Difficulty)

Problem Statement: Given a natural number M and Q queries of form T,R:

• T = 1: Count numbers that are divisors of both M and R.
• T = 2: Count numbers that are divisors of M and divisible by R.
• T = 3: Count numbers that are divisors of M but NOT divisible by R.
• Constraints: M, R ≤ 10¹², Q ≤ 10⁸

My Approach: Precomputed divisors of M for efficiency. Used GCD properties to quickly determine required counts. Each query was processed in O(log M), leading to an overall O(Q log M) complexity.

Results

Final results were announced a week later, and the Top 100 students were selected for the Walmart Global Tech Summer Internship 2025.

Verdict:

I was selected for the SWE Summer Internship 2025 at Walmart Global Tech India!

Key Takeaways & Advice

1. Speed and Accuracy Matter: The problems are solvable, so almost everyone attempts them. The differentiating factor is how quickly and accurately you solve them.
2. Strict Proctoring Rules: Walmart follows very strict proctoring. Any suspicious activity (e.g., looking away from the screen) can lead to disqualification.

Topics to Focus On:

• Graph Algorithms: DSU, Tarjan’s Algorithm, BFS, DFS
• Recursion & Backtracking
• Dynamic Programming (DP)
• Number Theory & GCD-based problems

Final Thoughts

The Walmart Sparkplug Internship selection process was a rigorous and competitive experience, pushing my problem-solving skills to the limit. The questions tested both fundamental CS knowledge and advanced algorithmic thinking. If you’re preparing for this challenge, make sure to practice under time constraints, focus solving questions on Leetcode and other platforms, and maintain accuracy under pressure. Additionally, participating in weekly contests can significantly improve problem-solving speed. A great way to build consistency is by solving Problem of the Day, which helps reinforce concepts regularly.

Best of luck to all future aspirants! 🚀