// SET OPERATIONS
// Frans Coenen
// Dept Computer Science, University of Liverpool
// 28 June 1999
// Revised: Tuesday 30 August 2005

import java.util.*;

class SetOperations {

    // ------------------ FIELDS ------------------------
	
	/** Instance of Scanner class. */
    private static Scanner keyboardInput = new Scanner(System.in);
    /** Array structure to represent an integer set. */
    private int[] integerSet = null;
	
	// ------------------ CONSTRUCTOR ------------------------
    
    public SetOperations(int numElements) {
    	if (numElements>0) integerSet = new int[numElements];
		}
	
    // ------------------ SET INPUT METHODS ------------------------

    /** Input a set of elements, includes error check in case of duplicate element. */

    public void inputSet() {
		// Loop till set instantiated
		System.out.println("Enter " + integerSet.length + " set elements.");
		for (int index=0;index<integerSet.length;) {
	    	int newElement = keyboardInput.nextInt();
	    	if (noDuplicates(newElement,index)) {
	    		integerSet[index] = newElement;
	    		index++;
	    		}
			else System.out.println("ERROR: Duplicate element " + newElement);
	    	}
		System.out.println();
		}
    
    /** Check for duplicates, return true if non found, false otherwise. 
    @param newElement the new element to be included in the integer set.
    @param currentEnd the current end of the array representing the set of integers to be
    input. */
    
    private boolean noDuplicates(int newElement, int currentEnd) {
        boolean noDuplicatesFound = true;
	
		// Loop through array so far
		for (int index=0;index<currentEnd;index++) {
	    	if (integerSet[index] == newElement) return(!noDuplicatesFound);
	    	}
	
		// Return
		return(noDuplicatesFound);
		}
    
    // ------------------ SET INTERSECTION METHODS ------------------------
    
    /** Create the intersection set between this integer set and the given set.
    @param set2 the given set.
    @return the intersection set.    */
    
    public SetOperations intersection(SetOperations set2) {
    	// Get size of intersection and create intersection set
    	int intersectionSize = numIntersectingElements(set2);
    	SetOperations set3   = new SetOperations(intersectionSize); 
    	
    	// Create intersection set (if intersection exists)
    	if (intersectionSize>0) {
    		int index3 = 0;
    		// Loop through this set. */
			for(int index1=0;index1<integerSet.length;index1++) {
				// Loop through given set. */
				int length = set2.getSetSize();
	    		for(int index2=0;index2<length;index2++) {
	    			// Compare
	    			if (integerSet[index1] == set2.getElementAtIndexN(index2)) {
		    			set3.setElementAtIndexN(index3,integerSet[index1]);
		    			index3++;
		    			break;
		    			}
		    		}
	    		}
	    	}
	    
	    // End
	    return(set3);
	    }
	    
    /* Determine number of intersecting elements between this set and the given set.
    @param set2 the given set.
    @return The number of intersections.   */
    
    private int numIntersectingElements(SetOperations set2) {
		// Check this integer set
		if (integerSet==null) return(0);
		
		// Check set2
		int length = set2.getSetSize();
		if (length==0) return(0);
		
		// Otherwise process
		int numElements=0;
		// Loop through this set. */
		for(int index1=0;index1<integerSet.length;index1++) {
			// Loop through given set (length value from above). */
	    	for(int index2=0;index2<length;index2++) {
	    		// Compare
	    		if (integerSet[index1] == set2.getElementAtIndexN(index2)) {
		    		numElements++;
		    		break;
		    		}
	    		}
	    	}
	    
		// Return. 
		return(numElements);    
		}
	
	// ------------------ GET AND SET METHODS ------------------------
	
	/** Gets the length (set size) of this integer set.
	@return the set size. */
	
	public int getSetSize() {
		int setSize = 0;
		
		if (integerSet!=null) setSize = integerSet.length;
		
		return(setSize);
		}
		
	/** Gets the value of the element in this integer set at index n.
	@param n the given index.
	@return the value at the given index in this integer set. */
	
	public int getElementAtIndexN(int n) {
		return(integerSet[n]);
		}
		
	/** Sets the value of the element in this integer set at index n.
	@param n the given index.
	@param value the value to be associated with the given index in this integer set. */
	
	public void setElementAtIndexN(int n, int value) {
		integerSet[n] = value;
		}
		
    // ------------------ SET INPUT METHODS ------------------------
    
    /** To string method */
    
    public String toString() {
    	String s = "{";
    	
    	// Test for empty set
    	if (integerSet!=null) {
    		s = s + integerSet[0];
			for(int index=1;index<integerSet.length;index++) {
	    		s = s + "," + integerSet[index];
	    		}
	    	}
	
		// End
		s = s + "}";
		return(s);
		}
    }