8 min read When Greedy Works: The Exchange Argument Greedy algorithms make the locally optimal choice at each step. They are provably correct […] Read article
9 min read Strings appear in roughly 25-30% of coding interviews. Unlike arrays or trees, string problems have a concentrated set of patterns […] Read article
7 min read Interval problems are a reliable interview topic at every level. The core patterns repeat across dozens of problems – learn […] Read article
11 min read Shortest path problems appear in nearly every graph interview. The key skill is recognizing which algorithm applies to the given […] Read article
10 min read Range query problems appear frequently in competitive programming and technical interviews. Knowing which data structure to reach for – and […] Read article
7 min read Core Entities and Schema The recommendation engine centers on four entities. User: user_id, preferences JSONB, created_at. Item: item_id, category, features […] Read article
5 min read Sliding Window Maximum – Monotonic Deque (LC 239) O(n) solution using a monotonic decreasing deque storing indices. Each element is […] Read article
6 min read Chinese Remainder Theorem (CRT) CRT solves systems of congruences: given x ≡ ai (mod mi) where mi are pairwise coprime, […] Read article
8 min read Why Sorting Algorithms Still Matter in Interviews Interviewers at top tech companies still ask about sorting not to test memorization, […] Read article
8 min read Scope and Requirements A payment processing platform handles money movement between buyers and sellers through external payment processors (Stripe, Adyen, […] Read article