Keith_Number.java

import java.util.*;  
class KeithNumberExample1  
{  

static boolean isKeith(int x)  
{  
ArrayList<Integer> terms=new ArrayList<Integer>();    
int temp = x, n = 0;     
while (temp > 0)  
{        
terms.add(temp%10);    
temp = temp/10;    
n++;  
}  
//reverse the List  
Collections.reverse(terms);  
int next_term = 0, i = n;  
while (next_term < x)  
{  
next_term = 0;  

for (int j=1; j<=n; j++)  
next_term = next_term + terms.get(i-j);  
terms.add(next_term);  
i++;  
}  
 
return (next_term == x);  
}  

public static void main(String[] args)  
{  

if (isKeith(19))  
System.out.println("Yes, the given number is a Keith number.");  
else  
System.out.println("No, the given number is not a Keith number.");  
if(isKeith(742))  
System.out.println("Yes, the given number is a Keith number.");  
else  
System.out.println("No, the given number is not a Keith number.");  
if(isKeith(4578))  
System.out.println("Yes, the given number is a Keith number.");  
else  
System.out.println("No, the given number is not a Keith number.");  
}  
}