// Online question from the sample final exam
// I further refined my answer from original as I developed it
// Beth Katz - April 2009

import java.util.Scanner;

public class Final {

	final static int MaxItems = 100;

	public static void main(String[ ] args) {
		int[ ] inventory = new int[MaxItems];
		Scanner input = new Scanner(System.in);

		int numItems = fillInventory(inventory, input);
		sell(inventory, numItems, input);
	}

	// fills inventory array and returns the number of possible items
	// for user to choose
	public static int fillInventory(int[ ] inventory, Scanner input) {
                int count = 0;
                int amount;
		System.out.println("Please enter the inventory amounts:");
		amount = input.nextInt( ); // read before loop
		while (amount >= 0) {
			inventory[count] = amount;
			count++;
	                amount = input.nextInt( ); // read at bottom of loop
		}

		System.out.println(count + " items read.");
		return count;
	}

	// sell items from inventory array 
	public static void sell(int[ ] inventory, int items, Scanner input) {
		int current;

		System.out.println("Please enter item numbers:");
		while (input.hasNextInt( )) {
			current = input.nextInt( );
			if (current < 0 || current >= items) {
				System.out.println(current 
					+ " is not a valid items number."
					+ " Should be from 0 to " + (items-1));
			} else {
				reduceStock(inventory, items, current);
			}
		}
	}

	// reduce stock in inventory[itemNum] if it is available
	// reports unavailability or that it was sold and remaining stock
	public static void reduceStock(int[ ] inventory, int items, int itemNum) {
		if (inventory[itemNum] <= 0) {
			System.out.println("Item number " + itemNum 
				+ " is not in stock");
		} else {
			inventory[itemNum]--;
			System.out.println("Item number " + itemNum + " sold, "					+ inventory[itemNum] + " remains"); 
		}
	}
}