Design a Set Data Structure

To design a Set without duplicates, I would start by defining a class that wraps a dynamic array. For storage, I prefer a Hash Map approach over a simple sorted array because it offers O(1) average time complexity for lookups and insertions, whereas a sorted array requires O(log n) or O(n) depending on the operation. The core mechanism involves a hash function that maps input values to array indices. Since collisions are inevitable, I would implement separate chaining, where each array index points to a linked list of elements sharing the same hash. When adding an element, I compute its hash, traverse the corresponding bucket to check for existence, and only append if unique. For removal, I locate the bucket and unlink the specific node. If the load factor exceeds a threshold like 0.75, I trigger a rehashing operation to double the array size and redistribute elements. While a raw array is simpler, it forces linear scans for every operation, making it inefficient for large datasets. A Hash Map provides the necessary speed but introduces overhead in managing pointers and handling collisions. This balance aligns well with Meta's focus on scalable systems where latency matters, ensuring our operations remain fast even as the dataset grows significantly.