5 articles
Master Segment Trees and Binary Indexed Trees for FAANG interviews: range sum, min, max queries, point updates, lazy propagation, 2D BIT, and full problem index with complexity reference.
LC 307 Range Sum Query Mutable is the canonical benchmark for range query data structures. BIT solves it in O(log n) per operation; Segment Tree generalizes to any associative query. Master both before your next FAANG interview.
Count smaller elements to the right of every index using a Binary Indexed Tree (Fenwick Tree) with coordinate compression. The cleanest O(n log n) solution every interviewer expects.
Count pairs (i, j) with i less than j and nums[i] greater than twice nums[j]. The classic Hard problem for modified merge sort and BIT counting — the two techniques every senior interviewer expects.
Complete Segment Tree and Fenwick Tree cheatsheet for FAANG interviews: BIT template, segment tree template, lazy propagation, 2D BIT, decision guide, and full problem index.