7 articles
Learn how to merge all nodes between consecutive zeros in a linked list into a single sum node in O(n) time and O(1) space. A clean simulation problem from LeetCode 2181 that tests in-place pointer manipulation and linked list traversal confidence.
Traverse an m×n matrix in spiral order. Master the boundary-shrinking technique — maintain top, bottom, left, right walls and peel layer by layer. Covers edge cases, visual dry run, common bugs, Python & JavaScript solutions, and follow-ups like Spiral Matrix II.
LC 2 Add Two Numbers is one of the most iconic interview problems at Amazon, Google, and Microsoft where you simulate grade-school addition on two reversed linked lists digit by digit. Master the carry propagation technique with Python and JavaScript solutions, visual dry run, and common pitfalls.
LC 445 Add Two Numbers II is a medium interview problem at Amazon and Google where numbers are stored most-significant-digit first, requiring stacks or list reversal to process from LSB. Learn the optimal stack-based solution with Python and JavaScript, dry run, and the key difference from LC 2.
Simulate a baseball scoring game using a stack to handle score records, doubles, sum operations, and cancellations in O(n) time. A clean stack-simulation problem that tests your ability to model stateful operations with LIFO access.
Find the minimum operations to return to the root folder by simulating file system navigation with a stack depth counter in O(n) time and O(1) space. A clean warm-up problem testing stack simulation and boundary conditions.
Simulate asteroid collisions where right-moving asteroids accumulate on the stack and left-moving ones destroy smaller ones on collision. A clean application of the collision-simulation stack pattern asked at Amazon and Bloomberg.