Gusto Coding Interview Questions
25 Gusto 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 Gusto interviewer values, and a FAQ section.
Showing 12 problems of 25
- #3mediumfrequently asked
3. Longest Substring Without Repeating Characters
Find the length of the longest substring with all unique characters. Gusto asks this as a sliding-window archetype — they want to see a clean window-shrink step that jumps the left pointer past the duplicate, not just nudges it one step.
- #15mediumfrequently asked
15. 3Sum
Find all unique triplets in the array that sum to zero. Gusto asks this to push beyond Two Sum — they want to see you sort first, lock one element, then use two pointers on the remainder while carefully skipping duplicates.
- #49mediumcommonly asked
49. Group Anagrams
Group strings that are anagrams of each other. Gusto asks this to test hash-map design and key construction — the sorted-string key is the canonical approach, but they may push you to the character-count key for O(n·k) without sorting.
- #56mediumfrequently asked
56. Merge Intervals
Merge all overlapping intervals. Gusto's scheduling and payroll features make this a naturally grounded problem — think PTO blocks, pay-period windows, or benefits-eligibility ranges. They want clean comparator logic and a crisp overlap condition.
- #139mediumcommonly asked
139. Word Break
Determine if a string can be segmented into words from a dictionary. Gusto asks this to test DP thinking — specifically whether you can define the right subproblem and build the table bottom-up without getting tangled in overlapping recursion.
- #146mediumfrequently asked
146. LRU Cache
Design a cache that evicts the least-recently-used item when it's full. Gusto asks this because caching is real infrastructure in their payroll platform — they want to see the hash map + doubly-linked list composition and hear you explain why each data structure is needed before writing any code.
- #198mediumcommonly asked
198. House Robber
Maximise the sum of non-adjacent elements. Gusto asks this as a clean introductory DP problem — they want you to derive the recurrence yourself and then compress the O(n) space solution to O(1) without being prompted.
- #200mediumcommonly asked
200. Number of Islands
Count the number of islands in a grid. Gusto uses this to introduce graph traversal in a 2D setting — they want to see BFS or DFS with in-place marking, and to hear you articulate why each approach is equivalent before choosing one.
- #207mediumcommonly asked
207. Course Schedule
Determine whether all courses can be finished given prerequisite constraints — which is a cycle detection problem on a directed graph. Gusto asks this to test topological sort and graph reasoning in a domain they understand well: dependency graphs in their payroll and benefits configuration.
- #238mediumfrequently asked
238. Product of Array Except Self
Compute, for each index, the product of all other elements — without using division. Gusto asks this to test whether candidates see the prefix-suffix decomposition and can then optimise it to O(1) extra space by computing the suffix product on the fly.
- #322mediumfrequently asked
322. Coin Change
Find the minimum number of coins needed to make up an amount. Gusto's payroll and benefits domain makes this a grounded problem — think minimum transaction splits for expense reimbursement. They want bottom-up DP with a clear recurrence, not naive recursion.
- #347mediumcommonly asked
347. Top K Frequent Elements
Return the k most frequent elements. Gusto asks this to test frequency counting combined with efficient selection — they want to hear about bucket sort to get O(n) rather than defaulting to heap-sort at O(n log k).