Cognizant Junior Software Engineer Interview Questions and Answers for Freshers

What is the probability of picking a red ball out of 10 balls with 2 red, 5 blue, and 3 orange?

• There are 2 red balls out of 10 total balls

• The probability of picking a red ball is 2/10 or 1/5

• The probability can also be expressed as 20%

Abstract class can have both abstract and non-abstract methods, while functional interface can have only one abstract method.

• Abstract class can have constructors, fields, and methods, while functional interface can only have one abstract method.

• Abstract class can have abstract and non-abstract methods, while functional interface can only have one abstract method.

• Abstract class can provide default implementations for methods, while functional interface cannot.

• Example: Abstract...read more

To reverse an array of numbers, iterate through the array and swap elements from start to end.

• Iterate through the array using two pointers, one starting from the beginning and the other from the end.

• Swap elements at the two pointers and move the pointers towards the center until they meet.

• Example: Input array [1, 2, 3, 4, 5], after reversing becomes [5, 4, 3, 2, 1].

Hashmap is a data structure that stores key-value pairs and uses hashing to quickly retrieve values based on keys.

• Hashmap uses an array to store key-value pairs.

• Keys are hashed to determine the index where the value will be stored.

• Collision handling techniques like chaining or open addressing are used to deal with multiple keys hashing to the same index.

• Retrieving a value involves hashing the key to find the index and then accessing the value stored at that index.

• Example: Has...read more

Multithreading is the ability of a CPU to execute multiple threads concurrently, while synchronization is the coordination of multiple threads to ensure data consistency.

• Multithreading allows multiple threads to run concurrently on a single CPU core.

• Synchronization is used to coordinate access to shared resources among multiple threads.

• Examples of synchronization mechanisms include locks, semaphores, and monitors.

• Multithreading can improve performance by utilizing idle CPU ti...read more

Data types are classifications of data items that determine the possible values and operations that can be performed on them.

• Data types define the type of data that a variable can hold, such as integers, strings, or booleans.

• Examples of data types include int (integer), float (floating point number), char (character), and bool (boolean).

• Data types also determine the size of the variable in memory and the range of values it can store.