Closest Room

For each query (preferred, minSize), find the roomId whose size is at least minSize that minimizes abs(id - preferred) (breaking ties by smaller id), or return -1 if none exist. With n up to 1e5 this is typically solved by sorting rooms and queries by size and maintaining an ordered set (balanced BST / sorted list) of eligible roomIds so you can binary-search the nearest id per query in O(log n).