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.
![LCA of 5 and 1, then of 5 and 4, in [3,5,1,6,2,0,8] with 2 having 7,4 overview diagram](/blogs/lca-in-a-binary-tree-explained-tracing-5-and-4-in-3-5-1-6-2-0-8/diagrams/hero.svg)
Master LCA in a binary tree (not BST) by tracing nodes 5, 1, and 4 in [3,5,1,6,2,0,8]. Understand the bottom-up DFS mental model and handle missing nodes.
![Round-trip [1, 2, 3, null, null, 4, 5] overview diagram](/blogs/serialize-and-deserialize-a-binary-tree-explained-1-2-3-null-null-4-5-round-trip/diagrams/hero.svg)
Learn how to serialize and deserialize a binary tree by tracing the exact round-trip for tree [1, 2, 3, null, null, 4, 5] using preorder traversal.
![LCA of 2 and 8, then of 2 and 4, in BST [6,2,8,0,4,7,9] overview diagram](/blogs/lca-in-a-bst-explained-finding-lca-for-2-8-and-2-4-in-6-2-8-0-4-7-9/diagrams/hero.svg)
Master Lowest Common Ancestor in BSTs. Trace LCA(2,8) and LCA(2,4) in tree [6,2,8,0,4,7,9] using the BST sorting property as a decision map.
![Is [5,4,6,null,null,3,7] a BST? overview diagram](/blogs/validate-a-bst-explained-tracing-5-4-6-null-null-3-7/diagrams/hero.svg)
Learn how to validate a binary search tree without falling into the local-check trap. Trace through [5,4,6,null,null,3,7] using the bounded window mental model.
Master binary tree diameter by tracing a path that bypasses the root entirely through node 2. Understand recursive height accumulation with a worked example.
