Coupang Coding Interview Questions
26 Coupang coding interview problems with full optimal solutions — 13 easy, 10 medium, 3 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Coupang interviewer values, and a FAQ section.
- #1easyfoundational
1. Two Sum
Find two indices in an array whose values sum to a target — Coupang uses this as a warm-up to test hash-map fluency before pivoting to inventory pricing problems.
- #2easyfoundational
2. Valid Parentheses
Validate a string of brackets using a stack — Coupang asks this to gauge stack reasoning before search-query parsing rounds.
- #3easyfoundational
3. Merge Two Sorted Lists
Merge two sorted linked lists into one sorted list — Coupang uses it to test pointer hygiene before merging delivery-route streams.
- #4easyfoundational
4. Remove Duplicates from Sorted Array
In-place dedupe of a sorted array — Coupang asks this to test pointer-pair fluency before SKU-list deduplication problems.
- #5easyfoundational
5. Remove Element
Remove all occurrences of a value in-place — Coupang uses this as a warm-up to test pointer logic before stock-clear list problems.
- #6easyfoundational
6. Search Insert Position
Binary-search for an insert index — Coupang uses this to test binary-search instincts that show up later in price-range filter problems.
- #7easyfoundational
7. Plus One
Increment a big integer represented as a digits array — Coupang uses this to check carry-propagation logic before order-number generator problems.
- #8easyfoundational
8. Merge Sorted Array
Merge two sorted arrays in-place, mirroring how Coupang merges sorted delivery slot batches for same-day routing.
- #9easyfoundational
9. Best Time to Buy and Sell Stock
Find the max profit from one buy-sell pair, mirroring how Coupang detects best price gaps in fluctuating SKU pricing for peak-event throughput.
- #10easyfoundational
10. Contains Duplicate
Detect whether any value appears twice in an array, mirroring how Coupang's returns-processing pipeline deduplicates RMA submissions.
- #11easyfoundational
11. Valid Anagram
Decide whether two strings are anagrams, mirroring how Coupang's Korean e-commerce search ranking normalizes query tokens.
- #12easyfoundational
12. Majority Element
Find the element that appears more than n/2 times, mirroring how Coupang's same-day delivery routing identifies the dominant origin warehouse per zone.
- #13easyfoundational
13. Move Zeroes
Move all zeroes to the end of an array while preserving the order of non-zeros, mirroring how Coupang's returns processing pushes invalidated SKUs to a quarantine tail without rewriting the active inventory.
- #14mediumfoundational
14. Add Two Numbers
Add two numbers stored as reverse-order linked lists, mirroring how Coupang's order-totalization pipeline streams partial sums across digit-precision boundaries during peak-event throughput.
- #15mediumfoundational
15. Longest Substring Without Repeating Characters
Find the longest substring without repeats, mirroring how Coupang's Korean e-commerce search ranking computes max-distinct windows over user query history.
- #16mediumfoundational
16. 3Sum
Find all unique triplets that sum to zero, mirroring how Coupang's bundle-pricing engine identifies SKU combinations that hit a target promotional discount during peak-event throughput.
- #17mediumfoundational
17. Container With Most Water
Find two lines that form the largest water container, mirroring how Coupang's truck-loading planner picks the pair of pallet heights that maximize same-day delivery routing volume.
- #18mediumfoundational
18. Group Anagrams
Group strings that are anagrams of each other, mirroring how Coupang's Korean e-commerce search ranking clusters tokens that normalize to the same canonical form for retrieval.
- #19mediumfoundational
19. Product of Array Except Self
Compute the product of all elements except each index without division, mirroring how Coupang's recommendation system computes per-SKU lift signals while excluding the current item from the cohort.
- #20mediumfoundational
20. Search in Rotated Sorted Array
Find a target in a rotated sorted array in O(log n), mirroring how Coupang's same-day delivery routing locates a slot in a partially rotated time-window index after midnight pivot.
- #21mediumfoundational
21. Coin Change
Compute the fewest coins to make an amount, mirroring how Coupang's checkout engine selects the minimum-count promotion stack to reach a target Korean e-commerce search ranking discount.
- #22mediumfoundational
22. Word Break
Decide whether a string can be segmented into dictionary words, mirroring how Coupang's Korean e-commerce search ranking segments user queries against an in-memory product-name lexicon.
- #23mediumfoundational
23. Number of Islands
Count connected land regions in a grid, mirroring how Coupang's same-day delivery routing partitions warehouses into connected coverage zones from a 2D capacity map.
- #24hardfoundational
24. Median of Two Sorted Arrays
Find the median of two sorted arrays in O(log) time, mirroring how Coupang's same-day delivery routing computes the median dispatch time across two pre-sorted regional batches without merging them.
- #25hardfoundational
25. Trapping Rain Water
Compute how much rainwater is trapped between bars, mirroring how Coupang's returns-processing pipeline estimates buffer capacity between fulfillment-center bottlenecks during peak-event throughput.
- #26hardfoundational
26. Merge k Sorted Lists
Merge k sorted linked lists into one sorted list, mirroring how Coupang's same-day delivery routing merges sorted dispatch streams from k regional warehouses during peak-event throughput.