Added merge sort

src/zutil/algo/sort/MergeSort.java

@@ -0,0 +1,135 @@
+package zutil.algo.sort;
+
+import zutil.algo.sort.sortable.SortableDataList;
+
+
+public class MergeSort{
+
+	/**
+	 * Sorts the given list with Merge sort
+	 * 
+	 * @param list is the list to sort
+	 */
+	public static void sort(int[] list){	
+		if(list == null) 
+			return;
+		
+		sort(list, 0, list.length);
+	}
+
+	/**
+	 * This method is the array splitting method 
+	 * that recursively splits the array in two.
+	 * 
+	 * @param list is the list to sort
+	 * @param start is the starting index of the sub list
+	 * @param stop is the end index of the sub list
+	 */
+	protected static void sort(int[] list, int start, int stop){
+		if(stop-start <= 1) return;
+
+		int pivot = start+(stop-start)/2;
+		sort(list, start, pivot);
+		sort(list, pivot, stop);
+
+		merge(list, start, stop, pivot);
+	}
+
+	/**
+	 * This method is the merger, after the array 
+	 * has been split this method will merge the 
+	 * two parts of the array and sort it.
+	 * 
+	 * @param list is the list to merge
+	 * @param start is the start of the first sublist
+	 * @param stop is the end of the second sublist
+	 * @param pivot is the end index for the first list and the beginning of the second.
+	 */
+	protected static void merge(int[] list, int start, int stop, int pivot){
+		int length = pivot-start;
+		int[] tmp = new int[stop-start];
+
+		for(int i=0; i<tmp.length ;++i){
+			tmp[i] = list[start+i];
+		}
+
+		int index1 = 0;
+		int index2 = length;
+		for(int i=start; i<stop ;++i){
+			if( index2 < stop-start && (index1 >= length || tmp[index1] > tmp[index2]) ){
+				list[i] = tmp[index2];
+				++index2;
+			}
+			else {
+				list[i] = tmp[index1];
+				++index1;
+			}
+		}
+	}
+	
+	
+	/**
+	 * Sorts the given list with Merge sort, 
+	 * this is slower than the one with int[] array
+	 * 
+	 * @param list is the list to sort
+	 */
+	public static void sort(SortableDataList<?> list){	
+		if(list == null) 
+			return;
+		
+		sort(list, 0, list.size());
+	}
+
+	/**
+	 * This method is the array splitting method 
+	 * that recursively splits the array in two.
+	 * 
+	 * @param list is the list to sort
+	 * @param start is the starting index of the sub list
+	 * @param stop is the end index of the sub list
+	 */
+	protected static void sort(SortableDataList<?> list, int start, int stop){
+		if(stop-start <= 1) return;
+
+		int pivot = start+(stop-start)/2;
+		sort(list, start, pivot);
+		sort(list, pivot, stop);
+
+		merge(list, start, stop, pivot);
+	}
+
+	/**
+	 * This method is the merger, after the array 
+	 * has been split this method will merge the 
+	 * two parts of the array and sort it.
+	 * @param <T>
+	 * 
+	 * @param list is the list to merge
+	 * @param start is the start of the first sublist
+	 * @param stop is the end of the second sublist
+	 * @param pivot is the end index for the first list and the beginning of the second.
+	 */
+	@SuppressWarnings("unchecked")
+	protected static <T> void merge(SortableDataList<T> list, int start, int stop, int pivot){
+		int length = pivot-start;
+		Object[] tmp = new Object[stop-start];
+
+		for(int i=0; i<tmp.length ;++i){
+			tmp[i] = list.get( start+i );
+		}
+
+		int index1 = 0;
+		int index2 = length;
+		for(int i=start; i<stop ;++i){
+			if( index2 < stop-start && (index1 >= length || ((Comparable)tmp[index1]).compareTo(tmp[index2]) > 0 )){
+				list.set(i, (T)tmp[index2]);
+				++index2;
+			}
+			else {
+				list.set(i, (T)tmp[index1]);
+				++index1;
+			}
+		}
+	}
+}

src/zutil/algo/sort/sortable/SortableArrayList.java

@@ -13,6 +13,10 @@ public class SortableArrayList<T> implements SortableDataList<T>{
 		return list.get(i);
 	}
 	
+	public void set(int i, T o){
+		list.set(i, o);
+	}
+
 	public int size() {
 		return list.size();
 	}

src/zutil/algo/sort/sortable/SortableComparableArray.java

@@ -12,6 +12,10 @@ public class SortableComparableArray implements SortableDataList<Comparable>{
 		return list[i];
 	}
 	
+	public void set(int i, Comparable o){
+		list[i] = o;
+	}
+
 	public int size() {
 		return list.length;
 	}

src/zutil/algo/sort/sortable/SortableDataList.java

@@ -4,11 +4,20 @@ public interface SortableDataList<T>{
 	
 	/**
 	 * Returns a is a specific index i the list
+	 * 
 	 * @param i is the index
 	 * @return
 	 */
 	public T get(int i);
 	
+	/**
+	 * Sets an Object in the specified index
+	 * 
+	 * @param i is the index
+	 * @param o is the Object
+	 */
+	public void set(int i, T o);
+	
 	/**
 	 * Returns the size of the list
 	 * 

src/zutil/algo/sort/sortable/SortableIntArray.java

@@ -11,6 +11,10 @@ public class SortableIntArray implements SortableDataList<Integer>{
 		return list[i];
 	}
 
+	public void set(int i, Integer o){
+		list[i] = o;
+	}
+	
 	public int size() {
 		return list.length;
 	}

src/zutil/algo/sort/sortable/SortableLinkedList.java

@@ -13,6 +13,10 @@ public class SortableLinkedList<T> implements SortableDataList<T>{
 		return list.get(i);
 	}
 	
+	public void set(int i, T o){
+		list.set(i, o);
+	}
+
 	public int size() {
 		return list.size();
 	}

src/zutil/image/filters/MedianFilter.java

@@ -142,6 +142,10 @@ public class MedianFilter extends ImageFilterProcessor{
 			return data[ getY(i) ][ getX(i) ][ channel ];
 		}
 		
+		public void set(int i, Integer o){
+			data[ getY(i) ][ getX(i) ][ channel ] = o;
+		}
+
 		public int size() {
 			return cols * rows;
 		}

src/zutil/test/SortTestSimple.java

@@ -1,4 +1,5 @@
 package zutil.test;
+import zutil.algo.sort.MergeSort;
 import zutil.algo.sort.QuickSort;
 import zutil.algo.sort.SimpleSort;
 import zutil.algo.sort.sortable.SortableIntArray;
@@ -20,10 +21,12 @@ public class SortTestSimple extends TestCase {
 		}
 		
 		long time = System.currentTimeMillis();
-		//SimpleSort.bubbleSort(new SortableIntArray(array));
+		//SimpleSort.bubbleSort( new SortableIntArray(array) );
-		//SimpleSort.selectionSort(new SortableIntArray(array));
+		//SimpleSort.selectionSort( new SortableIntArray(array) );
-		SimpleSort.insertionSort(new SortableIntArray(array));
+		//SimpleSort.insertionSort( new SortableIntArray(array) );
-		//QuickSort.sort(new SortableIntArray(array));
+		//QuickSort.sort( new SortableIntArray(array) );
+		//MergeSort.sort( array );
+		MergeSort.sort( new SortableIntArray(array) );
 		time = System.currentTimeMillis() - time;
 		
 		System.out.println("\n--------------------------------------------");