N26 Coding Interview Questions
25 N26 coding interview problems with full optimal solutions — 13 easy, 9 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 N26 interviewer values, and a FAQ section.
Showing 3 problems of 25
- #23hardfoundational
23. Sliding Window Maximum
Given an array and a window size k, return the maximum in each window as it slides left to right. N26 uses this for real-time peak-debit detection in their fraud-monitoring stream.
- #24hardfoundational
24. Find Median from Data Stream
Design a structure that supports adding numbers and querying the median in better than O(n) per op. N26 ports this to streaming the rolling median transaction value per customer for outlier scoring.
- #25hardfoundational
25. LFU Cache
Design a cache that evicts the least frequently used key, breaking ties by recency, with O(1) get and put. N26 uses this for FX-rate caching, where high-volume corridors (EUR-USD) should stay hot while one-off corridors get evicted.