Pregunta de entrevista de Azuga

there were 3 rounds. round 1: online coding cum MCQ round a)Kadane's algo(maximum sum subarray), b)simple SQL queries - JOIN, GROUP BY concept round 2: JAVA questions + coding question a)multi threading, b)how to make immutable class, c)equals and hashCode method for HashMap, d)Integer Constant Pool, e) find all list of pythagorean triplets in a given array (optimised solution was asked) round 3: Design + Problem solving round a) explain how kafka messaging works, can partitions of a topic be placed in different servers b) how to define java compile version and packaging type in a pom file c) Write a program for a simple calculator with undo and redo functions.