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Task/Sorting-algorithms-Strand-sort/Java/sorting-algorithms-strand-sort.java

@@ -0,0 +1,46 @@
+import java.util.Arrays;
+import java.util.LinkedList;
+
+public class Strand{
+	// note: the input list is destroyed
+	public static <E extends Comparable<? super E>>
+	LinkedList<E> strandSort(LinkedList<E> list){
+		if(list.size() <= 1) return list;
+
+		LinkedList<E> result = new LinkedList<E>();
+		while(list.size() > 0){
+			LinkedList<E> sorted = new LinkedList<E>();
+			sorted.add(list.removeFirst()); //same as remove() or remove(0)
+			for(Iterator<E> it = list.iterator(); it.hasNext(); ){
+				E elem = it.next();
+				if(sorted.peekLast().compareTo(elem) <= 0){
+					sorted.addLast(elem); //same as add(elem) or add(0, elem)
+					it.remove();
+				}
+			}
+			result = merge(sorted, result);
+		}
+		return result;
+	}
+
+	private static <E extends Comparable<? super E>>
+	LinkedList<E> merge(LinkedList<E> left, LinkedList<E> right){
+		LinkedList<E> result = new LinkedList<E>();
+		while(!left.isEmpty() && !right.isEmpty()){
+			//change the direction of this comparison to change the direction of the sort
+			if(left.peek().compareTo(right.peek()) <= 0)
+				result.add(left.remove());
+			else
+				result.add(right.remove());
+		}
+		result.addAll(left);
+		result.addAll(right);
+		return result;
+	}
+	
+	public static void main(String[] args){
+		System.out.println(strandSort(new LinkedList<Integer>(Arrays.asList(3,1,2,4,5))));
+		System.out.println(strandSort(new LinkedList<Integer>(Arrays.asList(3,3,1,2,4,5))));
+		System.out.println(strandSort(new LinkedList<Integer>(Arrays.asList(3,3,1,2,4,3,5,6))));
+	}
+}