Compunnel Interview Questions, Process, and Tips

BFS and DFS are traversal algorithms used in graphs and trees.

• BFS stands for Breadth First Search and explores the graph level by level.

• DFS stands for Depth First Search and explores the graph by going as deep as possible before backtracking.

• BFS uses a queue data structure while DFS uses a stack or recursion.

• BFS is useful for finding the shortest path while DFS is useful for finding all possible paths or cycles.

• BFS has...read more

Joins in SQL are used to combine data from two or more tables based on a related column between them.

• Joins are used to retrieve data from multiple tables in a single query.

• There are different types of joins such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN.

• The columns used to join the tables must have the same data type and name.

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.colu

Query to find second largest salary of an employee.

• Use ORDER BY and LIMIT to sort and select the second highest salary.

• Assuming table name as 'employees' and salary column name as 'salary'.

• SELECT salary FROM employees ORDER BY salary DESC LIMIT 1,1;

Abstract class can have implementation while interface cannot. A class can implement multiple interfaces but can only inherit from one abstract class.

• Abstract class can have constructors while interface cannot.

• Abstract class can have non-abstract methods while interface can only have abstract methods.

• Abstract class can have instance variables while interface cannot.

• A class implementing an interface must implement all i...read more