Roambee Interview Questions and Answers

Diameter of a binary tree is the longest path between any two leaf nodes.

• Calculate the height of left and right subtrees recursively.

• Calculate the diameter recursively using the formula max(left_height + right_height + 1, max(left_diameter, right_diameter)).

• Return the maximum diameter.

To find interchanged terms from an AP series

• Identify the common difference between terms

• Swap the positions of adjacent terms

• Check if the new series is also an AP

• Repeat until no more interchanged terms can be found

Database indexing is a technique to improve the performance of database queries.

• Indexing creates a data structure that allows for faster retrieval of data.

• Indexes are created on one or more columns of a table.

• Queries that use indexed columns can be executed faster.

• Indexes can be clustered or non-clustered.

• Clustered indexes determine the physical order of data in a table.

• Non-clustered indexes create a separate structure...read more

LRU caching is a technique to store frequently used data in cache memory to improve performance.

• LRU stands for Least Recently Used.

• It removes the least recently used item from the cache when the cache is full.

• It uses a doubly linked list and a hash map to implement the cache.

• When an item is accessed, it is moved to the front of the list.

• When the cache is full, the item at the end of the list is removed.

• Example: Java Li...read more

Producer-consumer problem involves synchronization between threads to avoid race conditions.

• Producer produces data and adds it to a shared buffer

• Consumer consumes data from the shared buffer

• Synchronization is required to avoid race conditions

• Code example: https://www.geeksforgeeks.org/producer-consumer-solution-using-threads-in-java/

To check if a tree is a BST or not.

• Traverse the tree in-order and check if the values are in ascending order.

• For each node, check if its value is greater than the maximum value of its left subtree and less than the minimum value of its right subtree.

• Recursively check if the left and right subtrees are also BSTs.

Reverse a single linked list.

• Iterate through the list and change the direction of the pointers

• Keep track of the previous, current and next nodes

• Set the head of the list to the last node after reversing

Print all anagrams of same type in same line from array of Strings

• Create a HashMap with sorted string as key and list of anagrams as value

• Iterate through array and add each string to corresponding list in HashMap

• Print all values in HashMap

Java 8 introduced lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions allow functional programming in Java.

• Functional interfaces are interfaces with a single abstract method.

• Streams provide a way to process collections of data in a functional way.

• Default methods allow interfaces to have implementation.

• Date and Time API improvements.

• Nashorn JavaScript engine added.