net.sf.cotelab.euler.Problem20 Maven / Gradle / Ivy

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package net.sf.cotelab.euler;

import java.math.BigInteger;


/**
 * A solution for Project Euler Problem 20.
 * The problem statement is
 * here.
 * @author Al Cote'
 */
public class Problem20 {
	/**
	 * @param args unused.
	 */
	public static void main(String[] args) {
		BigInteger bang = BigInteger.ONE;
		BigInteger term = BigInteger.ONE;
		String bangString;
		long sum = 0;
		
		for (int n = 0; n < 100; ++n) {
			bang = bang.multiply(term);
			term = term.add(BigInteger.ONE);
		}
		
		bangString = bang.toString();
		System.out.println("bangString = " + bangString);
		
		for (int i = 0; i < bangString.length(); ++i) {
			String digitString = bangString.substring(i, i + 1);
			long digitLong = Long.parseLong(digitString);
			
			sum += digitLong;
		}
		
		// 648
		System.out.println("sum = " + sum);
	}
}