CONCEPT BLOGS
Multi-phase guides with mental models, worked examples, diagrams, and real edge cases — the public form of Learnisim AI's conceptual learning. Read here; train it interactively in the app.
![Merge [[1,4,5],[1,3,4],[2,6]] overview diagram](/blogs/merge-k-sorted-lists-explained-tracing-1-4-5-1-3-4-2-6/diagrams/hero.svg)
Master Merge k Sorted Lists with a complete visual trace of [[1,4,5], [1,3,4], [2,6]]. Build the min-heap mental model step by step.
Master cloning linked lists with random pointers. Trace the interleaved interweaving model using the 7→13→11→10→1 working example to achieve $O(1)$ space complexity.
![Window max of [1, 3, -1, -3, 5, 3, 6, 7] k = 3 overview diagram](/blogs/sliding-window-maximum-deque-explained-tracing-1-3-1-3-5-3-6-7/diagrams/hero.svg)
Master the sliding window maximum pattern with a monotonic deque by tracing nums = [1, 3, -1, -3, 5, 3, 6, 7] step-by-step.
![Water trapped by [0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1] overview diagram](/blogs/trapping-rain-water-explained-tracing-0-1-0-2-1-0-1-3-2-1-2-1/diagrams/hero.svg)
Master the trapping rain water problem using a two-pointer elevation valley mental model, traced step by step on [0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1].
