inital

package edu.bu.ec504.hw1p1;

/**

 * Attempts to approximate the number of distinct elements seen so far.

 */

public abstract class DistinctCounter {

    // CONSTRUCTORS

    /**

     * This constructor cannot be used.

     */

    private DistinctCounter() {

        state = new Integer[0];

    };

    /**

     * Constructs an object backed by a given memory size.

     * @param stateSize The size of the memory backing, in number of integers.

     */

    public DistinctCounter(int stateSize) {

        state =new Integer[stateSize];

    }

    /**

     * Creates a DistinctCounter object from a given initial state.

     * @param initialState The output of a call to {@link #currentState()} on some DistinctCounter object.

     */

    public DistinctCounter(Integer[] initialState) {

        state = new Integer[initialState.length];

        for (int ii=0; ii<initialState.length; ii++)

            state[ii]=initialState[ii];

    }

    // OPERATIONAL

    /**

     * Log a new element that is seen.

     * @param newElement The element that was seen.

     */

    abstract void see(String newElement);

    /**

     *

     * @return A guess of the number of distinct elements that were seen.

     */

    abstract Integer numDistinct();

    // INFORMATIONAL

    /**

     * outputs the current state of the DistinctCounter

     * */

    public Integer[] currentState() {

        return state;

    }

    // FIELD

    final private Integer[] state;

}

package edu.bu.ec504.hw1p1;

import java.util.Arrays;

public class Main {

    public static void main(String[] args) {

	// write your code here

    }

}