// Marty Stepp, CSE 142, Autumn 2008
// This program contains various methods for printing numbers.
// It demonstrates "fencepost problems" where you want to print
// n numbers separated by n-1 spaces, commas, etc.

import java.util.*;

public class PrintNumbers {
	public static void main(String[] args) {
		printNumbers(5);
		printNumbers(12);
		printNumbers(1);
		printPrimes(50);
	}
	
	// Prints all prime numbers up to the given maximum integer.
	// For example, printPrimes(50) prints:
	// [2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 50]
	public static void printPrimes(int max) {
		System.out.print("[2");
		for (int i = 3; i <= max; i++) {
			if (countFactors(i) == 2) {
				System.out.print(" " + i);
			}
		}
		System.out.println("]");
	}
	
	// Returns the number of factors of the given integer n.
	// For example, countFactors(60) returns 12 because 1, 2, 3, 4, 6,
	// 8, 10, 12, 15, 20, 30, and 60 are factors of 60.
	// Assumes that n > 0.
	public static int countFactors(int n) {
		// check every integer i from 1--n,
		//    see if i is a factor of n
		int count = 0;
		for (int i = 1; i <= n; i++) {
			if (n % i == 0) {
				// i is a factor of n
				count++;
			}
		}
		
		return count;
	}
	
	// Prints the numbers 1-n separated by commas.
	// For example, printNumbers(5) prints 1, 2, 3, 4, 5
	public static void printNumbers(int n) {
		for (int i = 1; i < n; i++) {
			System.out.print(i + ", ");
		}
		System.out.println(n);
	} 
	
	// Alternative solution to printNumbers
	public static void printNumbers1(int n) {
		System.out.print(1);
		for (int i = 2; i <= n; i++) {
			System.out.print(", " + i);
		}
		System.out.println();
	} 
}