Why Google added BERT to search in 2019, how MLM training really works (15% mask, 80/10/10, WordPiece), and where encoder-only models still beat LLMs — rerank, classification, and OCR correction.
A comprehensive walkthrough of data structures used in search tasks like dictionary lookup, full‑text search, and autocomplete. Summarizes how 10 structures work and when to use them—including Trie, Double‑Array Trie, Inverted Index, Suffix Array, B+ tree, and LSM tree.
