merge.MergeSort.java Source code

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Here is the source code for merge.MergeSort.java

Source

// =============================================================================
//   Apache License
//   Version 2.0, January 2004
//   http://www.apache.org/licenses/
// =============================================================================

package merge;

import java.util.ArrayList;
import java.util.List;

import com.google.common.collect.Iterables;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;

/**
 * The MergeSort program simply take a series of input in a arraylist and sort
 * them using Merge Sort algorithm.
 * 
 * @author Sagir <sagir.pro@gmail.com>
 * @since 2014-08-09
 */

public class MergeSort {

    public static void main(String[] args) {
        MergeSort app = new MergeSort();
        List<Integer> input = Lists.newArrayList(4, 3, 543, 112, 23, 1);
        System.out.println("Input =" + input);
        Iterable<Integer> sorted = app.pertition(input);
        System.out.println("Sorted Data" + sorted);
    }

    private Iterable<Integer> pertition(List<Integer> input) {

        if (input.size() <= 1) {
            return input;
        }
        List<Integer> first = new ArrayList<Integer>();
        List<Integer> second = new ArrayList<Integer>();

        int middle = (int) Math.ceil((double) input.size() / 2);
        for (int i = 0; i < middle; i++) {
            first.add(input.get(i));
        }
        for (int i = middle; i < input.size(); i++) {
            second.add(input.get(i));
        }
        return mergesort(pertition(first), pertition(second));
    }

    private Iterable<Integer> mergesort(Iterable<Integer> first, Iterable<Integer> second) {

        Iterable<Integer> all = Iterables.mergeSorted(ImmutableList.of(first, second), Ordering.natural());

        return all;
    }

}