Hot100: Lowest Common Ancestor of a Binary Tree (Postorder Return Semantics ACERS Guide)
Subtitle / Summary The real difficulty of LeetCode 236 is not memorizing an LCA template. It is defining what each recursive call should return. Once that return value becomes stable, the whole problem collapses into a short and very clean postorder recursion. Reading time: 11-14 min Tags: Hot100, binary tree, LCA, DFS, postorder SEO keywords: Lowest Common Ancestor of a Binary Tree, LCA, postorder, DFS, LeetCode 236 Meta description: Learn LeetCode 236 from the recursive return-value semantics, with step-by-step derivation, engineering mappings, and runnable multi-language implementations. A — Algorithm Problem Restatement Given a binary tree, find the lowest common ancestor (LCA) of two given nodes p and q. ...