examples.java

/*
 *      examples.java
 *
 *      Copyright 2011 phra <phra@phra-b0x>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *      MA 02110-1301, USA.
 *
 *
 */


//import java.util.Iterator;
import java.util.Arrays;

public class examples {
    /**
     * @param args
     */
    public static void main(String args[]){

        miovettore numeri = new miovettore();

        try {if (args[0].equals("quicksort")) {

            System.out.println("vettore prima del quicksorting");
            System.out.println(Arrays.toString(numeri.a));
            numeri.quicksort(0,numeri.a.length-1);
            System.out.println("vettore dopo il quicksorting");
            System.out.println(Arrays.toString(numeri.a));

            }

        }   catch (ArrayIndexOutOfBoundsException e) {

            }
        try {if (args[0].equals("mergesort")) {

            System.out.println("vettore prima del mergesorting");
            System.out.println(Arrays.toString(numeri.a));
            numeri.mergesort(0,numeri.a.length-1);
            System.out.println("vettore dopo il mergesorting");
            System.out.println(Arrays.toString(numeri.a));

            }
        } catch (ArrayIndexOutOfBoundsException e) {

            System.out.println("HELP:");
            System.out.println("args[] vuoto.");
            System.out.println("> java examples mergesort");
            System.out.println("> java examples quicksort");

        }




    }
}

    class miovettore {

        int a[] = new int[]{20,10,15,12,12,4,3,2,34,654,56,34,2,34,18};
        int b[] = new int[100];

    void mergesort(int primo, int ultimo){

        if (primo<ultimo){

            int mezzo = (int)(primo+ultimo)/2;
            mergesort(primo,mezzo);
            mergesort(mezzo+1,ultimo);
            merge(primo,ultimo,mezzo);

        }
    }

    private void merge(int primo, int ultimo, int mezzo){

        int i,j,k,h;
        i = k = primo;j = mezzo+1;
        while ((i<=mezzo) && (j<=ultimo)) {

            if (this.a[i] <= this.a[j]){

                this.b[k] = this.a[i];
                i++;

            }
            else {

                this.b[k] = this.a[j];
                j++;

            }
            k++;
        }

        j = ultimo;
        for (h=mezzo;h>=i;h--){

            this.a[j] = this.a[h];

            j--;
        }

        for (j=primo;j<=k-1;j++){

            this.a[j] = this.b[j];
        }
    }

    void quicksort(int primo, int ultimo) {

        if (primo<ultimo) {

            int perno = perno(primo, ultimo);
            quicksort(primo,perno);
            quicksort(perno+1,ultimo);

        }
    }

    private int perno(int primo, int ultimo) {

        int x = this.a[primo];
        int j = primo;
        int i;
        for (i = primo;i <= ultimo;i++) {

            if (this.a[i] < x) {

                j++;
                swap(i,j);

            }
        }
        this.a[primo] = this.a[j];
        this.a[j] = x;
        return j;

    }

    private void swap(int uno, int due) {

        int temp = this.a[uno];
        this.a[uno] = this.a[due];
        this.a[due] = temp;

    }
}