HappyNumberUpTo1000.java

// WAP to define a method to check the number is happy number or not.
//A number is called happy if it leads to 1 after a sequence of steps where in each
//step number is replaced by sum of squares of its digit that is if we start with
//Happy Number and keep replacing it with digits square sum, we reach 1.
//EX : Input: n = 19 Output: True 19 is Happy Number,1^2 + 9^2 = 82,8^2 + 2^2 = 68
//6^2 + 8^2 = 100,1^2 + 0^2 + 0^2 = 1 As we reached to 1, 19 is a Happy Number.
// 1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68
public class HappyNumberUpTo1000 {
  public static void main(String[] args) {
    System.out.println("The Happy Number UpTo 1000 is : ");
    boolean j;
    int i=1;
    while (i<=1000)
    {
      j=isHappy(i);
      if (j==true)
      System.out.print(i+" ");
      i++;
    }
  }
  static boolean isHappy(int n) {
    while(n>9)
    {
      int sum = 0;
      while(n!=0)
      {
        int rem=n%10;
        sum=sum+(rem*rem);
        n=n/10;
      }
      n=sum;
    }
    if(n==1||n==7)
    return true;
    else
    return false;
  }
}