Walmart Labs interview questions

Advantage Shuffle

Given two equal-length arrays, permute nums1 to maximize the number of positions where nums1[i] > nums2[i]. This is a greedy matching problem: sort nums1 and…

Companies: Walmart Labs

Array · Greedy · Sorting · Two Pointers

Course Schedule II

Given numCourses and prerequisite pairs, return any ordering of courses that satisfies all prerequisites or an empty array if impossible — this is essentially computing…

Companies: Walmart Labs, Amazon, Anduril, Apple +11

Breadth-First Search · Depth-First Search · Graph Theory · Topological Sort

Delete and Earn

Aggregate points for each distinct number (value * frequency), then choose a subset of values maximizing sum with the constraint that taking value x forbids…

Companies: Walmart Labs, Walmart

Array · Dynamic Programming · Hash Table

Design an LLM agent with RAG and tools

Companies: Walmart Labs

Evaluate K-Fold Cross-Validation for Model Selection

Companies: Walmart Labs

Explain Transformer Components and Tree-Ensemble Trade-offs

Companies: Walmart Labs

Group Anagrams

Group the input strings into lists of anagrams — i.e., strings that contain the same multiset of letters — and return the groups in any…

Companies: Walmart Labs, Amazon, Apple, Arize Ai +14

Array · Hash Table · Sorting · String

Max Stack

Design a stack data structure that supports standard push, pop, and top operations, along with a getMax operation that retrieves (but does not remove) the…

Companies: Walmart Labs, Confluent, Everpure, LinkedIn

Design · Doubly-Linked List · Linked List · Ordered Set

Merge Intervals

Given a list of intervals, merge all overlapping (including touching endpoints) intervals and return the minimal set of non-overlapping intervals that cover them. Key pattern…

Companies: Walmart Labs, Amazon, Antithesis, Apple +16

Array · Quicksort · Sorting

Minimum Absolute Difference

Find all pairs of distinct integers that achieve the minimum absolute difference; the typical approach is to sort the array and collect adjacent pairs with…

Companies: Walmart Labs, Amazon

Array · Sorting

Number of Islands

Count the number of islands (4-directionally connected components of '1's) in an m×n binary grid. This is a connected-components/flood-fill problem typically solved with…

Companies: Walmart Labs, Amazon, Anduril, Apple +16

Array · Breadth-First Search · Depth-First Search · Matrix

Predict Next-Period Conversion Rate Using Historical Campaign Data

Companies: Walmart Labs

Sliding Window Maximum

Given an integer array and a window size k, return the maximum value for each contiguous subarray (sliding window) as it moves one step to…

Companies: Walmart Labs, Amazon, Bloomberg, D. E. Shaw +7

Array · Heap (Priority Queue) · Monotonic Queue · Queue

Sort Colors

Reorder an array of values 0, 1, and 2 in-place so all 0s come first, then 1s, then 2s (the Dutch National Flag problem); aim…

Companies: Walmart Labs, Amazon, Google, Microsoft

Array · Bubble Sort · Quicksort · Sorting

Top K Frequent Elements

Given an integer array and k, return the k most frequent elements — the core challenge is to count element frequencies and extract the top-k…

Companies: Walmart Labs, Amazon, Bloomberg, Google +9

Array · Bucket Sort · Counting · Divide and Conquer

Valid Parentheses

Check whether a string of parentheses/brackets is valid by ensuring every closing bracket matches the most recent unmatched opening bracket and the types and nesting…

Companies: Walmart Labs, Amazon, Apple, Bloomberg +9

Bracket Sequences · Stack · String

Word Break

Determine whether the string s can be segmented into a sequence of one or more words from wordDict (words may be reused). The core challenge…

Companies: Walmart Labs, Amazon, Google, Grammarly +3

Array · Brute-Force Search · Dynamic Programming · Hash Table