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00: Tree from a list & flattening it back to a list in Java

Hierarchical data with parent & child relationships are very common, and Java collection does not have a Tree data structure, hence it is a popular interview question. Further questions include tree data structure processing using recursiion & iteration. A Tree data structure can be represented as shown below.

Step 1: A simple Node.java class that encapsulates its value, parent node id & if any child nodes. It is important that “parent” is not included in the toString(..) method as it leads to Stack Overflow error due to recursive calls.

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01: Tree flattening example in Java with Generics

Q. Traverse the tree in depth and return a list of all passed nodes. It should handle different data types as Double, String, etc. The interface for the tree node is

A. Tree storing numbers: Tree storing text: #1. Define the …



02: Tree structure – calculate average recursively & iteratively in Java

Q. Complete the following “TreeProcessingImpl” class ….. so that the unit tests shown below pass? Skeleton Code



03: Tree traversal algorithms in Java

Q1. What are the different binary tree traversal mechanisms? A1. Traversing a tree means visiting all the nodes of a tree in order. Many different binary tree algorithms involve traversals. For example, if you wish to count the number of employees in an organizational chart you must visit each node….



04: Tree – Get root to leaf max sum in Java example

Q. Write code to traverse a tree and get the largest “root-to-leaf sum”? A “root-to-leaf sum” is a sum of the node values in a root-to-leaf path.

A. Let’s have a basic implementation of the above Node interface.



05: Is it a valid binary search tree (BST) ?

Q. Write code test if a given tree is a binary search tree (i.e. BST)? A. A binary search tree (BST) is a binary tree where each node satisfies the following conditions: 1) key in any node is larger than the keys in all nodes in that node’s left subtree…



06: Binary Tree – Sum Levels Java Example

Q. Write code to traverse a tree and return the sum of the values (Node.getValue()) of all nodes at the level N in the binary tree?

A. Let’s have a basic implementation of the above Node interface.



06: Binary Tree – Get root to leaf max sum in Java example

Q. Write code to traverse a binary tree and get the largest “root-to-leaf sum”? A “root-to-leaf sum” is a sum of the node values in a root-to-leaf path.

A. Let’s have a basic implementation of the above binary tree Node interface.



07: Tree – Sum Levels Java example

Q. Write code to traverse a tree and return the sum of the values (Node.getValue()) of all nodes at the level N in the tree?

A. Let’s have a basic implementation of the above Node interface.



08: Part-1: Basic Java Tree structure interview questions and coding questions

Java does not have a Tree class but you can define one. In my 10+ years as a Java developer, I have rarely used a Tree structure,  but when I do use it I find it to be a bit more complicated than working with other data structure. I have…



09: Part 2: Java Tree structure interview questions and coding questions

In the previous post entitled  Java Tree structure interview questions and coding questions — Part 1, we looked at a very simple Tree structure. In this example, let’s look at a more complex tree structure with generics. Q. Write classes for a Tripple tree structue as shown below? The Leaf…



10: Part-3: Java Tree structure interview and coding questions

This is an extension to Java Tree structure interview and coding questions — Part 2, and adds functional programming and recursion. Step 1: The Tree interface with get( ) method that returns either a Triple tree or Leaf data.

Step 2: The Leaf that implements the Tree interface. …



11: Part 4: Java Tree structure interview and coding questions

This is an extension to Java Tree structure interview questions and coding questions — Part 3 where recursion was used for FlattenTree interface. Let’s use iteration here. Step 1: The FlattenTree  interface.

Step 2: The iterative implementation IterativeFlattenTree. This uses a LIFO stack to push and pop Tree elements.



Recursion Vs Tail Recursion

Q1. Can you write a sample code that will count the number of “A”s in a given text? Show iterative, recursive, and tail recursive approaches?

“AAA rating”

A1.

Iteration



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