// CSE 373, Winter 2013, Marty Stepp
// This program is just a basic review of Java and Eclipse.
// We wrote methods to compute a factorial and to replicate a character.
// One new concept shown here is the use of the BigInteger class
// to represent arbitrarily large integer values.

import java.math.*;  // for BigInteger

public class Lecture01 {
	public static void main(String[] args) {
		System.out.println("Hello, world!");
		// String s = "12345";
		// int n = Integer.parseInt(s);
		// System.out.println(s + 1);
		// System.out.println(n + 1);

		System.out.println(factorial(40));
		System.out.println(nCopies(1000000, 'x'));
	}
	
	// Returns a string containing n copies of the character c.
	// For example, nCopies(5, 'x') returns "xxxxx".
	public static String nCopies(int n, char c) {
		StringBuilder s = new StringBuilder();
		for (int i = 0; i < n; i++) {
			s.append(c);
		}
		return s.toString();
	}
	
	// Returns n! = 1 * 2 * 3 * ... * n-1 * n.
	// Assumes n >= 0.
	public static BigInteger factorial(int n) {
		BigInteger x = BigInteger.valueOf(1);
		for (int i = 1; i <= n; i++) {
			x = x.multiply(BigInteger.valueOf(i));
		}
		return x;
	}
}