Coding tests are a very important process for software developers. In particular, algorithm problems provide a good opportunity to demonstrate your problem-solving skills. In this course, we will cover the problem of finding the Lowest Common Ancestor (LCA) in a tree structure.
Problem Description
In the given binary tree, the Lowest Common Ancestor (LCA) of two nodes A and B is the deepest node among the ancestors of nodes A and B. In other words, you need to find the nearest common ancestor along the paths of A and B.
Problem: Given a binary tree, write a function that takes the values of two nodes A and B and returns the Lowest Common Ancestor.
Input
- The root node of the binary tree is given.
- The values of nodes A and B are provided.
Output
- Returns the value of the Lowest Common Ancestor node.
Constraints
- The nodes in the binary tree are unique.
- Nodes always exist, and A and B must be included in the tree.
Algorithm Approach
To find the Lowest Common Ancestor, it is necessary to traverse the tree. A depth-first search (DFS) approach is used to recursively explore until each node is reached. The method to find A and B at each node is as follows.
- Examine the root node to see if it matches A or B.
- If the current node is null, return null.
- Recursively check the left child and the right child, and examine the results of both child calls.
- If both child calls return non-null results, the current node is the Lowest Common Ancestor.
- If only one child is non-null, that child is the Lowest Common Ancestor.