DAY 61 Binary Tree DFS: Depth and Similarity

Hello Everyone!

Week 13 started with a focus on Binary Tree Problems Using Depth-First Search (DFS). Today’s tasks required exploring binary tree structures to calculate depths and compare nodes, showcasing the elegance of recursive and iterative tree traversal. It felt like diving into a hierarchical world, understanding its structure step by step.

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How the Day Played Out

1. Maximum Depth of Binary Tree (Easy Difficulty)

   • Calculate the maximum depth of a binary tree.
   • The Strategy:
     • Used DFS recursively to traverse the tree.
     • At each node, calculated the depth by taking the maximum of the depths of the left and right subtrees, adding 1 for the current node.
   • The Fun Part:
     • Watching the recursion unfold and the depth stack build dynamically felt like exploring levels of a virtual tree.

2. Leaf-Similar Trees (Medium Difficulty)

   • Determine if two binary trees are leaf-similar, meaning they have the same leaf sequence.
   • The Strategy:
     • Used DFS to traverse both trees, collecting the leaf nodes in lists.
     • Compared the lists to check if the leaf sequences matched.
   • The Fun Part:
     • Extracting and comparing the leaf sequences was like finding and matching hidden treasures within the trees.

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What Made Today Special

1. Recursive Elegance:

   • Both problems showcased the power of recursion in traversing hierarchical structures efficiently.

2. Comparative Analysis:

   • Leaf-Similar Trees emphasized the importance of comparing data extracted during traversal, adding depth to the problem-solving process.

3. Visualizing Trees:

   • Thinking of the binary tree as a hierarchical map made the traversal process intuitive and engaging.

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Hello Everyone!

The week 13 portal began with Binary Tree Problems Using Depth-First Search (DFS) as its theme. As for today’s tasks, we had to search the depths of binary trees and compare their nodes and the elegance and beauty of recursive and iterative approaches to tree traversal. To carry on with the year, it was like diving into a world that saw a great hierarchy, in each step.

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Looking at the Events of the Day

1. MAX Depth of Binary Tree (Basic Difficulty)
   
   Constant –Predict the optimum depth of a binary tree

   • The Strategy:
     • We also used DFS recursively to traverse the tree. At calculation of some node, defined the depth of this node to be maximum of the depth of left and right subtrees plus ‘1’.
   • The Fun Part: The feel of watching recursion happening and seeing the depth stack being constructed proved to be like traversing through a virtual tree.

2. Leaf-Similar Trees (Medium Difficulty)
   
   To test if two binary trees are, or are not, each one’s leaf-similar the method is as follows;

   • The Strategy:
     • They used “DFS” to traverse both trees maintaining the lists of leaf notes. In case the first tree had a leaf sequence 1-2-4 while the second tree had the same sequence as 1-3-5, the program compared the two lists.
   • The Fun Part: Comparing the leaf sequences was like searching for a treasure and then finding it again in another tree.

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What made today special

1. Recursive Elegance:
   
   Both problems demonstrated how using recursion to move through a hierarchy would be efficient.

2. Comparative Analysis:
   
   Leaf-Similar Trees further stressed that only the data extracted at the time of traversal is considerable making the problem-solving deeper.

3. Visualizing Trees:
   
   Organizing the information within a binary tree form of a map was helpful because it made it easier to envision how the current level mapped onto the next level for traversal.

Key Takeaways

• DFS Simplifies Tree Traversals:
  
  DFS is beautifully used in problems like Maximum Depth of Binary Tree where to compute depths of the tree has been presented as a problem.

• Data Collection Matters:
  
  In Leaf-Similar Trees, using the DFS path to collect and compare data of a tree demonstrates how data extracted can be used to formulate solutions.

• Recursive Thinking is Powerful:
  
  Recursion is more simpler for a tree based problem, as it provides clarity and direct thinking as for how to get through each layer.

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Reflections

Maximum Depth of Binary Tree was quite straightforward which proved a comforting warming before addressing the chaotic Leaf-Similar Trees problem where we had to compare between two trees. Combined, these tasks established how DFS can be effectively used in the solution of binary tree problems.

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What’s Next?

Tomorrow, I’ll be working on Binary Tree DFS Problems again, doing Count Good Nodes in Binary Tree and Path Sum III. These tasks will involve tracking of values in the given problem and calculate the paths that possess some characteristics.

Thank you for reading my diary! Let’s continue to solve problems, continue learning and continue improving as one.