8 articles
Beyond the basic trie there is a rich landscape of advanced applications — XOR tries for maximum-XOR queries, prefix-and-suffix tries, ternary tries, compressed tries (PATRICIA), and persistent tries. Master these and you have the toolkit for half a dozen FAANG hards.
Master Tries for FAANG interviews: insert, search, prefix operations, Word Search II, autocomplete, XOR binary trie for max XOR, and 5-language implementations with full problem index.
LeetCode 1268 — return up to three lexicographically smallest products for every prefix of a search query. The trie autocomplete pattern that backs Google search, Amazon product search, and command palettes everywhere.
LeetCode 2416 — for each word, sum the scores of all its non-empty prefixes where score = number of words sharing that prefix. The counted trie pattern aggregates O(N times L) work into O(N times L) trie nodes with a count counter.
LeetCode 472 — find every word that can be formed by concatenating two or more shorter words from the same list. Trie accelerates the prefix-membership test inside a Word Break DP, turning O(2^L) brute force into O(N times L^2).
LeetCode 677 — design a structure supporting insert(key, value) and sum(prefix) returning the total of values for all keys with that prefix. The key trick is propagating delta sums along the trie path so prefix queries become a single O(L) walk.
LeetCode 2185 — count how many strings in words have pref as a prefix. The simple linear scan is optimal for a single query; the trie shines once you anticipate many queries against the same word list.
Map of every important trie variant you need for FAANG interviews — binary trie for XOR, reverse trie for suffix matching, counted trie for prefix scoring, offline trie for bounded queries, and the design patterns that compose them.