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Solution: Lowest Common Ancestor of a Binary Tree III

Explore the two-pointer approach to solve the Lowest Common Ancestor problem in a binary tree with parent references. Understand how simultaneous upward traversal from two nodes leads to identifying their common ancestor with optimal time and space complexity. This lesson helps you apply the two-pointer pattern to traverse trees without extra memory.

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Statement

You are given two nodes, p and q. The task is to return their lowest common ancestor (LCA). Both nodes have a reference to their parent node. The tree’s root is not provided; you must use the parent pointers to find the nodes’ common ancestor.

Note: The lowest common ancestor of two nodes, p and q, is the lowest node in the binary tree, with both p and q as descendants.

In a tree, a descendant of a node is any node reachable by following edges downward from that node, including the node itself. ...