Count Good Nodes in Binary Tree  Summary and Q&A
TL;DR
This content explains how to identify good nodes in a binary tree using DFS.
Key Insights
 👋 Good nodes in a binary tree are defined as those having the highest value on their path from the root.
 👋 Efficient traversal methods, such as DFS, provide a straightforward solution to find good nodes.
 👋 Each node must be evaluated in the context of the maximum value from the root to correctly classify it as good or not.
 😒 The use of a variable to keep track of current maximum values is essential during the traversal.
 👋 Good nodes can enhance understanding of tree structures and their hierarchical value distribution.
 👋 Analyzing examples can significantly clarify the method of identifying good nodes.
 💻 The problem demonstrates both practical algorithm application and theoretical understanding in computer science.
Transcript
hello everyone welcome back to lead coding today we are solving the problem called good note in a binary tree so we are given a binary tree and we have to return the number of good nodes in that tree so how do we classify your node to be a good node so a node is considered as good if it has the maximum value among all the nodes which comes in the p... Read More
Questions & Answers
Q: What are good nodes in a binary tree?
Good nodes are defined as nodes that have the highest value along the path from the root to that node. In order for a node to be classified as good, its value must be greater than or equal to the maximum value of all previous nodes traversed from the root.
Q: How can we implement the identification of good nodes?
The identification can be implemented using a depthfirst search (DFS) strategy. During the traversal, a variable is maintained to keep track of the maximum value encountered from the root to the current node. If the current node's value is greater than or equal to this maximum, it is counted as good.
Q: What time complexity is associated with solving the good nodes problem?
The time complexity of solving the problem is O(n), where n is the number of nodes in the binary tree. This efficiency is achieved through the DFS approach, which visits each node exactly once.
Q: Can you give an example of how to determine good nodes in a binary tree?
Consider a binary tree with root value 3, and children values 4 and 1. As you traverse, 3 is a good node. Moving to 4, it remains the maximum, marking it good as well. However, moving to 1, it fails the criteria as 4 is greater, thus is not good.
Summary & Key Takeaways

The problem involves counting "good nodes" in a binary tree, defined as nodes with the maximum value along the path from the root to that node.

An example is provided where the nodes are evaluated to determine which are "good" based on their maximum value in the path leading from the root.

A depthfirst search (DFS) approach is suggested for solving the problem efficiently with a time complexity of O(n).