10 articles
Master two optimal approaches to merge k sorted linked lists: min-heap for O(n log k) time and divide-and-conquer for O(n log k) with lower constant factors. A top-tier interview problem at Amazon, Google, Facebook, Microsoft, and Uber that tests your mastery of heaps and recursive merging.
Master Tarjan's SCC algorithm: a single DFS pass with discovery times, low-link values, and an explicit stack to identify all strongly connected components in O(V + E). The interview gold standard for directed graph decomposition, asked at Google, Meta, and Uber.
LeetCode 815 Bus Routes is deceptively hard. The trick is that BFS levels count buses, not stops, so the graph you traverse is a route graph. Master the stop-to-routes inversion that beats the time limit at FAANG interviews.
LeetCode 134 Gas Station is an Amazon, Uber, and Google favorite. Solve the circular-tour problem in a single linear pass using the running-tank greedy and a clean existence argument.
Master the computational geometry primitives every interviewer expects: cross product orientation, segment intersection, Graham scan convex hull, polygon area via shoelace, and point in polygon.
LC 17 Letter Combinations of a Phone Number is the cleanest cartesian-product backtracking template ever written. Master the digit-to-letter mapping, the per-position branching, and why the iterative BFS variant is asked at Amazon.
Design a calendar that rejects double bookings. The classic interval-overlap interview problem solved with sorted maps in O(log n) per booking — the foundation for every range scheduling system.
Solve LeetCode 227 Basic Calculator II using a stack to handle operator precedence for plus, minus, multiplication, and division. A FAANG interview classic at Google, Amazon, Meta, and Uber.
LeetCode 230 Kth Smallest Element in a BST — Amazon, Meta, Uber favorite. Iterative inorder with a stack stops at the kth pop in O(h+k) time.
LeetCode 1161 Maximum Level Sum returns the smallest level whose node-sum is largest. Solve in O(n) with BFS level-size snapshots — a common Amazon and Meta phone-screen question.