1582 articles
Find the longest substring that appears at least twice using binary search on the answer length combined with a Rabin-Karp rolling hash. A FAANG-level Hard problem solved in O(n log n) average time with full pseudocode in Python and JavaScript.
Design FreqStack to push values and pop the most frequent element with recency tie-breaking in O(1). Master the freq-map plus group-of-stacks pattern with a full visual dry run, common pitfalls, and Python and JavaScript solutions.
Master every binary search pattern used at FAANG interviews — classic exact match, left and right boundary, rotated array, binary search on answer, parity, and 2D matrix — with copy-pasteable templates and a 23-problem index.
LeetCode 704 — the foundational FAANG binary search problem solved in O(log n) using the classic three-way exact-match template with overflow-safe midpoint.
LeetCode 278 — find the first bad version among n versions in O(log n) API calls using left-boundary binary search, the canonical FAANG predicate-search problem.