Problem: Lowest Common Ancestor of a Binary Tree III

med

30 min

Understand how to find the lowest common ancestor of two nodes in a binary tree when parent pointers are available. This lesson helps you apply two-pointer strategies to navigate upward through the tree and determine the common ancestor, even without a root reference, enhancing your problem-solving skills for coding interviews.

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.

Constraints:

$-10^4 \leq$ Node.data $\leq 10^4$
The number of nodes in the tree is in the range $[2, 500].$
All Node.data are unique.
p != q
Both p and q are present in the tree.

⋮

Tap here to switch tabs

Problem

Ask

Submissions

Home

Courses

Grokking the Coding Interview Patterns

Problem: Lowest Common Ancestor of a Binary Tree III

med

30 min

Statement

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.

Constraints:

$-10^4 \leq$ Node.data $\leq 10^4$
The number of nodes in the tree is in the range $[2, 500].$
All Node.data are unique.
p != q
Both p and q are present in the tree.

Problem: Lowest Common Ancestor of a Binary Tree III

Statement

Example

Understand the problem

Figure it out!

Try it yourself

Problem: Lowest Common Ancestor of a Binary Tree III

Statement

Example

Understand the problem

Figure it out!

Try it yourself