#### Keith Number

P
```package com.thealgorithms.maths;

import java.util.*;

class KeithNumber {

// user-defined function that checks if the given number is Keith or not
static boolean isKeith(int x) {
// List stores all the digits of the X
ArrayList<Integer> terms = new ArrayList<Integer>();
// n denotes the number of digits
int temp = x, n = 0;
// executes until the condition becomes false
while (temp > 0) {
// determines the last digit of the number and add it to the List
// removes the last digit
temp = temp / 10;
// increments the number of digits (n) by 1
n++;
}
// reverse the List
Collections.reverse(terms);
int next_term = 0, i = n;
// finds next term for the series
// loop executes until the condition returns true
while (next_term < x) {
next_term = 0;
// next term is the sum of previous n terms (it depends on number of digits the number
// has)
for (int j = 1; j <= n; j++) {
next_term = next_term + terms.get(i - j);
}
i++;
}
// when the control comes out of the while loop, there will be two conditions:
// either next_term will be equal to x or greater than x
// if equal, the given number is Keith, else not
return (next_term == x);
}

// driver code
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
if (isKeith(n)) {
System.out.println("Yes, the given number is a Keith number.");
} else {
System.out.println("No, the given number is not a Keith number.");
}
in.close();
}
}
```  