CGI Group Software Engineer Interview Questions and Answers

Marker interfaces are used to indicate a specific property or behavior of a class without defining any methods.

• Marker interfaces do not contain any methods or fields.

• They are used to provide metadata about a class.

• Common examples include Serializable and Cloneable in Java.

• They help in implementing design patterns like Singleton.

Time complexity of hashmap operations is O(1) on average, but can be O(n) in worst case.

• HashMap operations like get, put, remove have constant time complexity O(1) on average due to hashing

• In worst case scenario, all keys hash to the same bucket resulting in linear search O(n)

• Rehashing occurs when load factor exceeds a threshold, increasing time complexity temporarily

Two common design patterns used in projects are Singleton and Observer patterns.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

Spring beans can have different scopes like singleton, prototype, request, session, and application.

• Singleton scope: Bean is created only once per Spring IoC container

• Prototype scope: Bean is created each time it is requested

• Request scope: Bean is created once per HTTP request

• Session scope: Bean is created once per HTTP session

• Application scope: Bean is created once per ServletContext

Sort the list of car models in reverse order

• Use a sorting algorithm like bubble sort or quicksort to rearrange the array in reverse order

• Alternatively, use built-in functions like sort() with a custom comparator function to achieve the same result

To reverse a number, convert it to a string, reverse the string, and convert it back to a number.

• Convert the number to a string

• Reverse the string

• Convert the reversed string back to a number