Continuing the Binary Search pattern! Capacity To Ship Packages Within D Days was a great example of “binary search on answer space” — setting low/high bounds and checking feasibility.
Find First and Last Position reinforced the left-bound / right-bound binary search template.
Deep-dived into BLOB / Object Storage — learned the pre-signed URL pattern (avoid routing files through backend), multipart uploads for large files, and why metadata should always be stored separately in SQL/NoSQL.