/*  This program will input a list of numbers from the user and then using some methods locate and remove all duplicates */

import java.util.Scanner;

public class Prog7_15
{
	public static void main(String[] args)
	{
		int[] array = new int[100];						// assume no more than 100 elements
		Scanner in = new Scanner(System.in);			// get the elements, this method returns the number of elements
		int number = getValues(in, array);
		System.out.print("Array before eliminating duplicates:  ");
		output(array, number);							// output the list before removing duplicates
		number = removeDuplicates(array, number);		// remove the duplicates, this method returns the new size of the array
		System.out.print("\n\nArray after eliminating duplicates:  ");
		output(array, number);							// output the list after removing duplicates
	}
	
	// this method input a list of values from the user entering each into an array and returns the number of elements input into the array
	public static int getValues(Scanner in, int[] a)
	{
		int number = 0;
		System.out.print("Enter a list of values, -999 to exit, no more than 100 total elements  ");
		int temp = in.nextInt();
		while(temp!=-999&&number<100)
		{
			a[number++]=temp;
			System.out.print("Enter next value, -999 to exit, no more than 100 total elements  ");
			temp = in.nextInt();	
		}
		return number;
	}
	
	// this method outputs all elements of the array on one line
	public static void output(int[] a, int number)
	{
		for(int i=0;i<number;i++)
			System.out.print("\t"+a[i]);
		System.out.println();
	}
	
	// this method iterates through an array to locate any duplicates, for instance it starts at a[0] and searches the rest of
	// the array for elements equal to a[0], if found, each duplicate is removed, it then moves on to a[1].  For each removed
	// element, the number of elements in the array (number) is decremented.  It returns number at the end so main will know
	// the new size of the array.
	public static int removeDuplicates(int[] a, int number)
	{
		for(int i=0;i<number;i++)			// iterate through the array
			for(int j=i+1;j<number;j++)		// iterate from the next element upward to compare each to a[i]
				if(a[i]==a[j]) 				// if a duplicate is found
				{							//			remove it and decrement number since there is 1 fewer element
					remove(a, j, number);	// a[j] is the duplicate, so we need to remove it by shifting a[j+1] through a[number-1] to the left 1 position
					number--;
				}
		return number;						// return this so main knows how many elements are left in the array
	}
	
	// this method shifts all elements from a[j+1] to a[number-1] down one to the left
	public static void remove(int[] a, int j, int number)
	{
		for(int i=j;i<number-1;i++)			// we stop at number-2 because we are shifting a[number-1] to a[number-2]
			a[i]=a[i+1];					// shift element one position to the left
	}
}