Sunny Number in Java

by Online Tutorials Library July 22, 2022

Sunny Number in Java

In this section, we will learn what is sunny numbers and how to create a Java program to find the sunny numbers. We will also create a Java program to find all the sunny numbers between the specified range.

Sunny Number

A number is called a sunny number if the number next to the given number is a perfect square. In other words, a number N will be a sunny number if N+1 is a perfect square.

Let’s understand it through an example.

Sunny Number Example

Suppose, we have to check if 80 is a sunny number or not.

Given, N=80 then N+1 will be 80+1=81, which is a perfect square of the number 9. Hence 80 is a sunny number.

Let’s take another number 10.

Given, N=10 then N+1 will be 10+1=11, which is not a perfect square. Hence 10 is not a sunny number.

Steps to Find Sunny Number

The logic is very simple. To find the sunny number, we need only to check whether N+1 is the perfect square or not.

Read or initialize a number (num).
Add 1 to the given number i.e. num+1.
Find the square root of num+1.
If the square root is an integer, the given number is sunny, else not a sunny number.

Let’s implement the above steps in a Java program.

Sunny Number Java Program

SunnyNumberExample1.java

  import java.util.*;   public class SunnyNumberExample1  {   //driver code   public static void main(String args[])   {   Scanner sc = new Scanner(System.in);  System.out.print(“Enter a number to check: “);  //reading a number from the user  int N=sc.nextInt();  //calling user-defined function   isSunnyNumber(N);   }       //function checks whether the given is a perfect square or not   static boolean findPerfectSquare(double num)   {   //finds the square root of the ggiven number  double square_root = Math.sqrt(num);   //if square root is an integer   return((square_root – Math.floor(square_root)) == 0);   }   //function that checks whether the given number is Sunny or not  static void isSunnyNumber(int N)   {   //checks N+1 is perfect square or not  if (findPerfectSquare(N + 1))   {   System.out.println(“The given number is a sunny number.”);   }   //executes if N+1 is not a perfect square  else  {   System.out.println(“The given number is not a sunny number.”);   }   }   }  

Output 1:

Enter a number to check: 80  The given number is a sunny number.

Output 2:

Enter a number to check: 670  The given number is not a sunny number.

Let’s create another Java program and find all the sunny numbers between a given range.

SunnyNumberExample2.java

  import java.util.Scanner;  public class SunnyNumberExample2  {  //user-defined function that determines all the sunny numbers  public static boolean isSunnyNumber(int number)   {  //determines the square root of number+1 using Math.sqrt() method  if(Math.sqrt(number+1)%1 == 0)  return true;  else   return false;  }  //driver code  public static void main(String args[])   {  //lr is lower range and ur is upper range  int lr = 0, ur = 0;  Scanner scan = new Scanner(System.in);  System.out.print(“Enter lower range: “);  //reads an integer (lr) from the user  lr = scan.nextInt();  System.out.print(“Enter upper range: “);  //reads an integer (ur) from the user  ur = scan.nextInt();  System.out.println(“The Sunny number from “+ lr + ” to “+ ur+” are: “);  for(int i=lr; i<=ur; i++)   {  //calling user-defined number  if(isSunny(i))  System.out.print(i +” “);  }  }  }  

Output:

Enter lower range: 1  Enter upper range: 1000  The Sunny number from 1 to 1000 are:   3 8 15 24 35 48 63 80 99 120 143 168 195 224 255 288 323 360 399 440 483 528 575 624 675 728 783 840 899 960

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