1582 articles
LeetCode 211 walkthrough — implement WordDictionary supporting add and search where the search query can contain a "." wildcard. The optimal solution combines a trie with DFS branching at every wildcard, a textbook FAANG interview pattern.
LeetCode 212 — find every dictionary word hidden in a board. The optimal solution builds a trie over the words and DFS-traverses the grid once, pruning entire branches the moment the path leaves the trie. A textbook FAANG hard problem.
LeetCode 648 — replace each word in a sentence with the shortest dictionary root that prefixes it. The trie walks one character at a time, returning the first isEnd we hit. A clean autocomplete-style problem.
LeetCode 421 — find the maximum XOR pair in an array of integers in O(N times 32) using a binary trie. The classic introduction to bit-trie pattern that powers competitive programming and database query optimisers.
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.