Nubank Coding Interview Questions
25 Nubank 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 Nubank interviewer values, and a FAQ section.
Showing 9 problems of 25
- #14mediumfoundational
14. Number of Islands
Count connected components of '1's in a 2D grid; Nubank uses it as an analog for clustering related KYC/fraud accounts on a relationship grid.
- #15mediumfoundational
15. LRU Cache
Design a Least-Recently-Used cache with O(1) get and put; a staple Nubank uses to probe whether candidates can pair a hash map with a doubly-linked list for hot-account caching.
- #16mediumfoundational
16. Merge Intervals
Merge a list of overlapping intervals into the minimum disjoint set; Nubank uses it as an analog for collapsing overlapping hold-amounts on a credit-card ledger.
- #17mediumfoundational
17. Binary Tree Level Order Traversal
Return a binary tree's node values level by level; Nubank uses BFS-with-level-snapshots to test queue discipline before deeper org-hierarchy / category-tree questions.
- #18mediumfoundational
18. Longest Palindromic Substring
Find the longest substring of s that reads the same forward and backward — Nubank uses expand-around-center to gauge whether you can avoid O(n^3) brute force under stress.
- #19mediumfoundational
19. Longest Increasing Subsequence
Find the length of the longest strictly increasing subsequence in an array; Nubank uses LIS to test DP fluency, often framed as longest rising balance trend in a checking account.
- #20mediumfoundational
20. Coin Change
Compute the fewest coins that sum to a target amount; Nubank loves this one as a stand-in for cash-out denominations problems on PIX/withdrawal flows.
- #21mediumfoundational
21. Number of Provinces
Count connected components in an adjacency-matrix graph; Nubank uses this as a clean Union-Find prompt that maps to clustering linked accounts during fraud-ring detection.
- #22mediumfoundational
22. Course Schedule II
Topologically order n courses given prerequisite edges; Nubank uses Kahn's algorithm as a stand-in for ordering dependent steps in a settlement DAG.