quick sort for linked list: done

Author: Ram swaroop

src/me/ramswaroop/linkedlists/QuickSort.java

@@ -0,0 +1,88 @@
+package me.ramswaroop.linkedlists;
+
+import me.ramswaroop.common.SingleLinkedList;
+import me.ramswaroop.common.SingleLinkedNode;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 7/21/15
+ * @time: 11:43 PM
+ */
+public class QuickSort {
+
+    public static <E extends Comparable<E>> SingleLinkedNode<E>[] partition(SingleLinkedNode<E> firstNode,
+                                                                            SingleLinkedNode<E> lastNode) {
+
+        SingleLinkedNode<E>[] partition = new SingleLinkedNode[4];
+        SingleLinkedNode<E> pivot = lastNode, curr = new SingleLinkedNode<>(null, firstNode), currNext, pivotNext;
+
+        while (curr.next != null && curr.next != lastNode) {
+            if (curr.next.item.compareTo(pivot.item) > 0) {
+                currNext = curr.next;
+                curr.next = currNext.next;
+                pivotNext = pivot.next;
+                pivot.next = currNext;
+                currNext.next = pivotNext;
+                continue;
+            }
+            curr = curr.next;
+        }
+
+        partition[0] = curr;
+
+        while (curr.next != pivot) {
+            curr = curr.next;
+        }
+        partition[1] = curr;
+
+        partition[2] = pivot.next;
+
+        while (curr.next != null) {
+            curr = curr.next;
+        }
+        partition[3] = curr;
+
+        return partition;
+
+    }
+
+    public static <E extends Comparable<E>> SingleLinkedNode<E> quickSort(SingleLinkedNode<E> firstNode,
+                                                                          SingleLinkedNode<E> lastNode) {
+
+        SingleLinkedNode<E> head = firstNode;
+        if (firstNode != lastNode) {
+            SingleLinkedNode<E> partition[] = partition(firstNode, lastNode);
+            head = quickSort(partition[0], partition[1]);
+            quickSort(partition[2], partition[3]);
+        }
+
+        return head;
+    }
+
+    public static <E extends Comparable<E>> SingleLinkedNode<E> quickSort(SingleLinkedNode<E> node) {
+        return quickSort(node, getLastNode(node));
+    }
+
+    public static <E extends Comparable<E>> SingleLinkedNode<E> getLastNode(SingleLinkedNode<E> node) {
+        SingleLinkedNode<E> curr = node;
+
+        while (curr != null && curr.next != null) {
+            curr = curr.next;
+        }
+
+        return curr;
+    }
+
+    public static void main(String a[]) {
+        SingleLinkedList<Integer> linkedList = new SingleLinkedList<>();
+        linkedList.add(23);
+        linkedList.add(4);
+        linkedList.add(45);
+        linkedList.add(11);
+        linkedList.add(7);
+        linkedList.printList();
+        linkedList.printList(quickSort(linkedList.head));
+    }
+}