eBay Coding Interview Questions
25 eBay coding interview problems with full optimal solutions — 8 easy, 12 medium, 5 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an eBay interviewer values, and a FAQ section.
Showing 5 problems of 25
- #4hardsometimes asked
4. Median of Two Sorted Arrays
eBay's pricing analytics team computes median transaction prices across two buyer segments in real time — combining sorted bid histories without merging them. Median of Two Sorted Arrays is the flagship O(log(m+n)) algorithm that eBay uses at the senior level to test binary search mastery beyond basic forms. The partition-based approach is notoriously tricky and strongly differentiates senior candidates.
- #23hardfrequently asked
23. Merge K Sorted Lists
eBay's search ranking system merges sorted result streams from k independent indices — seller inventory, product catalog, auction listings — into a single ordered result set. Merge K Sorted Lists is the algorithmic core. It elevates the two-list merge (LC 21) to a k-way problem requiring a min-heap, which eBay uses to separate candidates who truly understand priority queue mechanics.
- #42hardsometimes asked
42. Trapping Rain Water
eBay's data visualization team renders capacity charts for warehouse storage — thinking of elevation bars as bin capacities and water as overflow volume. Trapping Rain Water is a classic two-pointer problem that eBay uses at the hard level to test whether candidates can optimize from O(n) space (prefix/suffix arrays) to O(1) space (two-pointer) through clear reasoning.
- #84hardsometimes asked
84. Largest Rectangle in Histogram
eBay's seller analytics dashboard visualizes listing activity as bar charts — finding the largest contiguous block of equal or taller listings tells analysts about peak sustained activity windows. Largest Rectangle in Histogram is a stack-based hard problem that eBay uses to test monotonic stack mastery, one of the most powerful patterns for range-query problems.
- #127hardsometimes asked
127. Word Ladder
eBay's catalog team maps product category transitions — how many steps does it take to reclassify a listing from one category to a related one, changing only one attribute at a time? Word Ladder is a BFS shortest-path problem on an implicit graph that eBay uses to test graph construction, BFS level-tracking, and neighbor-generation efficiency.
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