Design & Data Structures

One family of Goldman coding questions asks you to build a small piece of a system while the interviewer watches. The scope is one structure, never a whole service. Think a cache that forgets its stalest entry, a stack that hands back its smallest element in constant time, or a tally that rolls name-and-score records into one number per person. The work is modest in size and exact in execution. You pick the two structures that fit, wire them together, and keep every operation inside the time bound you claimed.

Two shapes cover almost all of it. The first is aggregation: records arrive keyed by some id, a student and a grade, and you group them and reduce each group to a single value. The second is a designed data structure, where one hash map is not enough and you pair it with a linked list or a second stack so that lookup and update both stay fast. A Premium question is the aggregation Goldman is known for. A Premium question is the designed structure it returns to most. Learn to see which of the two a prompt wants and the code that follows is short.