/*
 * Paweł Bogaczewicz
 * projecteuler.net
 * problem 20
 * Find the sum of the digits in the number 100!
 */

package org.bogaczew.euler.problems;

import java.math.BigInteger;

public class Euler020 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		System.out.println("projecteuler.net #020");
		System.out.println("Find the sum of the digits in the number 100!\n");
		int n = 20;
		if (args.length == 1) {
			try {
				n = Integer.parseInt(args[0]);
			} catch (Exception e) {
				System.out.println("arg parse error. will use default n=" + n
						+ "\n\n");
			}
		}
		Euler020 euler = new Euler020();
		euler.sumDigits(euler.getFactorial(n).toString());

	}

	public BigInteger getFactorial(int n) {
		if (n < 0) {
			return BigInteger.ZERO;
		} else if (n > 0) {
			BigInteger factorial = BigInteger.ONE;
			for (int i = 1; i <= n; i++) {
				factorial = factorial.multiply(BigInteger.valueOf(i));
			}
			return factorial;
		} else {
			return BigInteger.ONE;
		}
	}

	public void sumDigits(String s) {
		long sum = 0;
		for (int i = 0; i < s.length(); i++) {
			sum += Long.parseLong(s.substring(i, i + 1));
			System.out.print(s.charAt(i)+"|");
		}
		System.out.println("\n"+sum);
	}
}