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Lowest Common Ancestor of a Binary Tree

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🧠 Before you code — what pattern fits?

Given a binary tree and two nodes p and q, return their lowest common ancestor (LCA): the lowest node that has both p and q as descendants (a node can be a descendant of itself).

([3,5,1,6,2,0,8,null,null,7,4], p=5, q=1) → 3

(…, p=5, q=4) → 5

🎬 Video explanation · Cracking FAANG

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