Wise Coding Interview Questions
26 Wise 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 Wise interviewer values, and a FAQ section.
Showing 26 problems of 26
- #1easyfoundational
1. Two Sum
Find two indices whose values sum to a target, a daily warm-up at Wise where matching one transfer leg to another is the bread and butter.
- #2easyfoundational
2. Valid Parentheses
Validate that a string of brackets is balanced — a classic stack warm-up before Wise drills you on ledger entries that must balance debits and credits.
- #3easyfoundational
3. Merge Two Sorted Lists
Merge two sorted linked lists into one — Wise frames this around merging two sorted FX rate feeds into a single time-ordered stream.
- #4easyfoundational
4. Remove Duplicates from Sorted Array
Dedup a sorted array in place — Wise sometimes wraps this around deduping repeated FX quote ticks before they hit the matching engine.
- #5easyfoundational
5. Remove Element
Remove all occurrences of a value in place — Wise frames this as scrubbing a failed-transfer flag from a batch payout array before settlement.
- #6easyfoundational
6. Search Insert Position
Find the index where a target should be inserted to keep an array sorted — Wise uses this to test if you can insert a new FX quote into a sorted price ladder.
- #7easyfoundational
7. Plus One
Increment a number represented as a digit array — Wise loves this because it directly probes integer-overflow thinking essential for money math.
- #8easyfoundational
8. Single Number
Find the one unpaired transaction in a stream where every other entry has a matching counter-entry — a tiny model of ledger reconciliation at Wise.
- #9easyfoundational
9. Linked List Cycle
Detect whether a singly linked list contains a cycle — a cheap probe of pointer hygiene, exactly the discipline Wise needs in their settlement engine.
- #10easyfoundational
10. Best Time to Buy and Sell Stock
Find the maximum profit from one buy/sell in an FX-style price series — a thinly disguised cross-border arbitrage matching question.
- #11easyfoundational
11. Contains Duplicate
Detect any duplicate value in an array — Wise uses this as a warm-up for double-debit detection in payment idempotency tests.
- #12easyfoundational
12. Missing Number
Find the missing value in 0..n with one slot absent — a clean stand-in for the missing-leg detector in a double-entry ledger.
- #13easyfoundational
13. Move Zeroes
Push zeros to the end of an array in place while preserving order — Wise treats this as a stand-in for cleaning up empty payment legs without losing real entries.
- #14mediumfoundational
14. Add Two Numbers
Sum two integers represented as digit linked lists with carry propagation — Wise uses this as the canonical money-math probe (no floats, ever).
- #15mediumfoundational
15. Longest Substring Without Repeating Characters
Find the longest unique-character window in a string — Wise uses it as a stand-in for the longest streak of unmatched ledger entries in a reconciliation scan.
- #16mediumfoundational
16. Container With Most Water
Pick two columns that hold the most water — Wise reframes this as picking the two FX liquidity pools that maximize a peer match.
- #17mediumfoundational
17. 3Sum
Find every triplet in an array that sums to zero — Wise uses it as a three-leg peer pooling probe (two senders cover one receiver).
- #18mediumfoundational
18. Group Anagrams
Bucket strings by anagram class — Wise treats this as the canonical hash-keyed bucketing problem behind their FX matching engine.
- #19mediumfoundational
19. Merge Intervals
Merge overlapping intervals into a minimal cover — Wise uses it as a stand-in for collapsing overlapping settlement windows in cross-border batches.
- #20mediumfoundational
20. Unique Paths
Count grid paths from top-left to bottom-right moving only right or down — Wise frames it as counting candidate FX routes through their corridor graph.
- #21mediumfoundational
21. Permutations
Generate every permutation of a distinct-integer array — Wise uses this to probe controlled backtracking, which is the same pattern as enumerating FX routing legs.
- #22mediumfoundational
22. Word Break
Decide if a string segments into dictionary words — Wise uses it as a stand-in for whether a multi-currency payment can be decomposed into legal corridor hops.
- #23mediumfoundational
23. LRU Cache
Design a get/put cache with O(1) eviction of the least recently used key — Wise probes this for FX rate caches in front of their pricing oracles.
- #24hardfoundational
24. Median of Two Sorted Arrays
Find the median across two sorted arrays in logarithmic time — Wise frames it as the mid-spread quote across two sorted FX order books.
- #25hardfoundational
25. Trapping Rain Water
Compute trapped water given an elevation map — Wise reframes it as the locked-up liquidity between two FX pool walls.
- #26hardfoundational
26. Merge k Sorted Lists
Merge k sorted linked lists into one — Wise reframes it as collapsing k ordered per-corridor settlement streams into a single FIFO ledger.