Java Developer

The idea is to generate all the possible subsequences using the bit masking technique. For each subsequence, check if it is a Harmonious subsequence or not. Take the maximum length of all the possible subsequences.

The steps are as follows:

• Initialize 'ANSWER' to 0, which denotes the longest length of the Harmonic subsequence.
• Iterate from ‘i’ = 0 to ‘2^N - 1’, where ‘N’ is the length of the given Array, ‘ARR’.
  • Initialize three integers ‘MIN_VALUE’, ‘MAX_VALUE’, and ‘COUNT_LENGTH’ with INT_MAX, INT_MIN, and 0 respectively which stores the minimum, maximum values of the current subsequence and length of the current subsequence respectively.
  • Iterate from ‘j’ = 0 to ‘N-1’:
    • If a jth bit of i is set and ‘MIN_VALUE’ is less than ARR[j], then update ‘MIN_VALUE’ to ARR[j].
    • If a jth bit of i is set and ‘MAX_VALUE’ is greater than ARR[j], then update ‘MAX_VALUE’ to ARR[j].
    • Increment the count as we are including the current element in the subsequence.
  • If the difference between the ‘MAX_VALUE’ and ‘MIN_VALUE’ is 1. It means it is a valid subsequence. Update 'ANSWER' to a maximum of 'ANSWER' and ‘COUNT_LENGTH’. Also, take care of the integer overflow.
• Return 'ANSWER’ as the final answer.

The Collection in Java is a framework that provides an architecture to store and manipulate the group of objects.
Java Collections can achieve all the operations that you perform on a data such as searching, sorting, insertion, manipulation, and deletion.
Java Collection means a single unit of objects. Java Collection framework provides many interfaces (Set, List, Queue, Deque) and classes (ArrayList
, Vector, LinkedList
, PriorityQueue
, HashSet, LinkedHashSet, TreeSet).

1. ArrayList implements the List interface. HashMap implements the Map interface.
2. ArrayList implements the List interface. HashMap implements the Map interface.
3. ArrayList stores element's value and maintains the indexes for each element. HashMap stores elements key & value pair. For each value, there must be a key associated with HashMap.
4. ArrayList stores only a single object. HashMap stores elements in Key and value pairs.
5. We get the element by specifying the index of it in ArrayList. The elements are being fetched by the corresponding Key in HashMap.
6. The ArrayList maintains the order of the objects they are inserted. HashMap does not provide a guarantee of the order in which they are inserted.

A REST API (also known as RESTful API) is an application programming interface (API or web API) that conforms to the constraints of REST architectural style and allows for interaction with RESTful web services. REST stands for representational state transfer and was created by computer scientist Roy Fielding.

The main difference between static and final is that the static is used to define the class member that can be used independently of any object of the class. In contrast, final is used to declare a constant variable or a method that cannot be overridden or a class that cannot be inherited.

There are many immutable classes like String, Boolean, Byte, Short, Integer, Long, Float, Double etc. In short, all the wrapper classes and String class is immutable. To create an immutable class, create a final class that have final data members.

Example :

public final class Employee 
{ 
final String pancardNumber; 
public Employee(String pancardNumber) 
{ 
this.pancardNumber=pancardNumber; 
} 
public String getPancardNumber(){ 
return pancardNumber; 
} 
} 
public class ImmutableDemo 
{ 
public static void main(String ar[]) 
{ 
Employee e = new Employee("ABC123"); 
String s1 = e.getPancardNumber(); 
System.out.println("Pancard Number: " + s1); 
} 
}