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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 class that encapsulates its value,

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01: Tree flattening example in Java

Q. Traverse the tree in depth and return a list of all passed nodes. It should handle different data types as Double, String, etc. The4 interface for the tree node is A. Tree storing numbers: Tree storing text: #1. … Read more ›...

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 Unit Tests A. Solution 1: Solution 2: Using recursion for getAverage(…) and iteration for getSum(…) Key Points #1: Recursion can cause stack overflow exception if you don’t properly define an exit condition. …...

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....

03: Understanding Big O notations

Q. Have you seen job advertisements requiring Java candidates to work in real-time or high volume transaction processing systems? If you are applying for such jobs, you can be quizzed on Big O notation. Here are some basics to brush up on. … Read more ›...

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. … Read more ›...

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...

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Java Interview FAQs

800+ Java Interview Q&As