Problem: Happy Number
Let the sum of the square of the digits of a positive integer S0 be represented by S1. In a similar way, let the sum of the squares of the digits of S1 be represented by S2 and so on. If Si = 1 for some i ³ 1, then the original integer S0 is said to be Happy number. A number, which is not happy, is called Unhappy number.
Console:
Let the sum of the square of the digits of a positive integer S0 be represented by S1. In a similar way, let the sum of the squares of the digits of S1 be represented by S2 and so on. If Si = 1 for some i ³ 1, then the original integer S0 is said to be Happy number. A number, which is not happy, is called Unhappy number.
For example,
7 is a Happy number since 7 -> 49 -> 97 -> 130 -> 10 -> 1 and
4 is an Unhappy number since 4 -> 16 -> 37 -> 58 -> 89 -> 145 -> 42 -> 20 -> 4.
Solve:
7 is Happy number-why? cause-
Lets see the following code:
7 is Happy number-why? cause-
72 = 49
42 + 92 = 16 + 81 = 97
92 + 72 = 81 + 49 = 130
12 + 32 + 02 =
1+9+0 = 10
12 + 02 = 1
4 is Unhappy number because it never return to 0Lets see the following code:
// ADLabs
import java.util.HashSet;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Set;
public class HappyNumber {
// used to tell if a number has already been checked
ArrayList checked = new ArrayList();
public static void main(String[] args) {
HappyNumber hn = new HappyNumber();
Scanner sc =new Scanner(System.in);
System.out.println("Happy Number Checker (to Stop enter 0)");
System.out.print("Enter Number : ");
int number = sc.nextInt();
//System.out.print(hn.sum_sq_digits(number));
//
while (number>0) {
if (hn.isHappy(number)) {
System.out.println(number + " is Happy Number :)");
}else {
System.out.println(number + " is UnHappy Number :(");
}
System.out.print("Enter Number : ");
number = sc.nextInt();
}
//
sc.close();
}
public boolean isHappy(int i) {
Set check = new HashSet();
while (check.add(i)) //add and check database and return true
{
i = sum_sq_digits(i); //return sum of 2
System.out.print(i +" ");
if (i==1)
break;
}
System.out.println("");
return i==1; // if i=1 return true
}
public int sum_sq_digits(int number){
int sum = 0;
while (number > 0)
{
sum += Math.pow(number % 10, 2);
number /= 10;
}
return sum;
}
}
Console:
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| Console Output |
