How do you find the Lowest Common Ancestor (LCA) in a binary tree?

For a general binary tree, use recursion: if current node is null or matches either target, return it. Recursively find LCA in left and right subtrees. If both return non-null, current node is LCA. If only one returns non-null, return that. Time complexity is O(n). For BST, leverage ordering: if both targets are smaller, go left; if both larger, go right; otherwise current node is LCA with O(h) time.