one

onesol.java

package com.vijayraj.learn;

import java.math.BigInteger;
import java.util.ArrayList;

public class Problem1 {

	public static void main(String args[])
	{
		//check if the sum is equal to the value
		int i = 1;
		while(true){
			int output = R(i);
			if(output==Integer.parseInt(args[0]) || output==0)
			{
				System.out.println("The answer is : " + i);
				break;
			}
			i++;
		}
	}
	
	public static int R(int n)
	{
		BigInteger factorial = Factorial4.factorial(n);
		int sum = sum(factorial.toString());
		System.out.println(n + " - " + factorial.toString() + " - " + sum);
		return sum;
	}
	
	public static int sum(String factorialString)
	{
		int length=factorialString.length();
		int sum = 0;
		
		for(int i=length-1; i>=0; i--)
		{
			sum+=(Character.getNumericValue(factorialString.charAt(i)));
		}
		
		return sum;
	}
	
	

}
/**
	 * This version of the program uses arbitrary precision integers, so it 
	 * does not have an upper-bound on the values it can compute. It uses an 
	 * ArrayList object to cache computed values instead of a fixed-size 
	 * array. An ArrayList is like an array, but can grow to any size. The 
	 * factorial() method is declared "synchronized" so that it can be safely 
	 * used in multi-threaded programs. Look up java.math.BigInteger and
	 * java.util.ArrayList while studying this class.
	 * Prior to Java 1.2, use Vector instead of ArrayList
	 */

	class Factorial4 {
	  protected static ArrayList<BigInteger> table = new ArrayList<BigInteger>(); // create cache
	  static 
	  { // Initialize the first element of the cache with !0 = 1.
	    table.add(BigInteger.valueOf(1));
	  }

	  /** The factorial() method, using BigIntegers cached in a ArrayList */
	  public static synchronized BigInteger factorial(int x) {
	    if (x < 0)
	      throw new IllegalArgumentException("x must be non-negative.");
	    for (int size = table.size(); size <= x; size++) {
	      BigInteger lastfact = (BigInteger) table.get(size - 1);
	      BigInteger nextfact = lastfact.multiply(BigInteger.valueOf(size));
	      table.add(nextfact);
	    }
	    return (BigInteger) table.get(x);
	  }

	  /**
	   * A simple main() method that we can use as a standalone test 
	   * program for our factorial() method.
	   */
	  public static void main(String[] args) {
	    for (int i = 0; i <= 50; i++)
	      System.out.println(i + "! = " + factorial(i));
	  }
	}