PayPal Coding Interview Questions
25 PayPal coding interview problems with full optimal solutions — 16 easy, 6 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 PayPal interviewer values, and a FAQ section.
Showing 3 problems of 25
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23. Median of Two Sorted Arrays
Find the median of two sorted arrays in O(log(min(m,n))) time without merging them. PayPal asks this hard binary-search problem to identify engineers who can handle statistical aggregations over large financial data streams where merging is prohibitively expensive.
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24. Trapping Rain Water
Compute the total volume of water trapped between bars of varying heights. PayPal asks this problem to gauge candidates' ability to reason about prefix/suffix aggregations — a pattern that underlies cumulative transaction balance calculations and risk exposure windows.
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25. Sliding Window Maximum
Return the maximum value in every sliding window of size k over an array in O(n) time. PayPal uses this deque-based problem to test candidates on streaming aggregation — a core primitive in real-time fraud scoring and transaction risk-window analysis.
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