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 5 problems of 25
- #4hardrarely asked
4. Median of Two Sorted Arrays
Find the median of two sorted arrays in O(log(m+n)). Gusto asks this for senior roles to test binary search reasoning under pressure — they want the binary search on partitions approach, and they watch whether you can maintain the invariant clearly without devolving into case chaos.
- #23hardcommonly asked
23. Merge K Sorted Lists
Merge k sorted linked lists into one. Gusto asks this as the natural escalation from Merge Two Sorted Lists — they want to see the divide-and-conquer approach or a min-heap, and they care that you recognise the O(Nk) naive solution is unacceptable.
- #41hardrarely asked
41. First Missing Positive
Find the smallest missing positive integer in O(n) time and O(1) extra space. Gusto asks this to test whether candidates can use the array itself as a hash map — the insight that the answer must lie in [1, n+1] is what unlocks the in-place solution.
- #42hardcommonly asked
42. Trapping Rain Water
Calculate how much rain water can be trapped between elevation bars. Gusto uses this as a harder two-pointer showcase — they want the O(1)-space two-pointer solution and to hear the invariant explained: 'water level at any position is determined by the shorter of the two tallest walls seen so far from each side.'
- #127hardrarely asked
127. Word Ladder
Find the shortest transformation sequence from beginWord to endWord changing one letter at a time. Gusto asks this to test BFS on implicit graphs — the graph is never explicitly built, and the neighbour-generation step (26 letter substitutions) is where candidates get bogged down without a clear strategy.