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.
![Find "ABCCED" on [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]] overview diagram](/blogs/word-search-on-a-board-explained-finding-abcced-in-a-3-4-matrix/diagrams/hero.svg)
Trace 'ABCCED' step-by-step through a 3×4 grid to master matrix backtracking, state exploration, and why standard string matching fails.
Learn N-Queens (n = 4) by tracing how to place 4 queens on a 4×4 board. Understand state space trees and backtracking step by step.
![Candidates [2, 3, 6, 7] target 7 overview diagram](/blogs/combination-sum-explained-tracing-2-3-6-7-for-target-7/diagrams/hero.svg)
Learn the backtracking pattern for Combination Sum by tracing candidates [2, 3, 6, 7] and target 7 step by step to avoid duplicate combinations.
![Unique permutations of [1, 1, 2] overview diagram](/blogs/permutations-with-duplicates-explained-unique-permutations-of-1-1-2/diagrams/hero.svg)
Learn how to generate unique permutations for duplicate arrays. Trace the decision tree for [1, 1, 2] step-by-step using the twin-skipping mental model.
![Unique subsets of [1, 2, 2] overview diagram](/blogs/subsets-with-duplicates-explained-unique-subsets-of-1-2-2/diagrams/hero.svg)
Learn how to generate unique subsets when input arrays contain duplicates, featuring a complete trace of [1, 2, 2] and a sorting-based skipping model.
