delete lesser nodes: done

Author: Ram swaroop

src/me/ramswaroop/linkedlists/DeleteLesserNodes.java

@@ -0,0 +1,71 @@
+package me.ramswaroop.linkedlists;
+
+import me.ramswaroop.common.SingleLinkedList;
+import me.ramswaroop.common.SingleLinkedNode;
+
+/**
+ * Created by IntelliJ IDEA.
+ *
+ * @author: ramswaroop
+ * @date: 6/30/15
+ * @time: 5:13 PM
+ */
+public class DeleteLesserNodes {
+
+    /**
+     * Delete a node from {@param list} if there are any nodes
+     * with values greater than node on the right hand side of the list.
+     *
+     * Example:
+     *
+     * Input:   12->15->10->11->5->6->2->3->NULL
+     * Output:  15->11->6->3->NULL
+     *
+     * Input:   10->20->30->40->50->60->NULL
+     * Output:  60->NULL
+     *
+     * Input:   60->50->40->30->20->10->NULL
+     * Output:  60->50->40->30->20->10->NULL
+     *
+     * @param list
+     * @param <E>
+     */
+    public static <E extends Comparable<E>> void deleteLesserNodes(SingleLinkedList<E> list) {
+
+        // reverse the list
+        ReverseSingleLinkedList.reverseList(list);
+
+        E max;
+        SingleLinkedNode<E> curr = list.getNode(0), prev = curr;
+
+        max = curr.item;
+
+        while (curr != null) {
+            if (curr.item.compareTo(max) >= 0) {
+                max = curr.item;
+                prev = curr;
+            } else {
+                prev.next = curr.next;
+            }
+
+            curr = curr.next;
+        }
+
+        // reverse the list
+        ReverseSingleLinkedList.reverseList(list);
+    }
+
+    public static void main(String a[]) {
+        SingleLinkedList<Integer> linkedList = new SingleLinkedList<>();
+        linkedList.add(00);
+        linkedList.add(11);
+        linkedList.add(22);
+        linkedList.add(33);
+        linkedList.add(44);
+        linkedList.add(55);
+        linkedList.add(66);
+        linkedList.printList();
+        deleteLesserNodes(linkedList);
+        linkedList.printList();
+    }
+}

src/me/ramswaroop/linkedlists/ReverseLinkedListInAlternateGroups.java

@@ -20,7 +20,7 @@ public class ReverseLinkedListInAlternateGroups<E extends Comparable<E>> extends
      * <p/>
      * Example:
      * Inputs:   1->2->3->4->5->6->7->8->9 and k = 3
-     * Output:   3->2->1->4->5->6->9->8->7.
+     * Output:   3->2->1->4->5->6->9->8->7
      *
      * @param node
      * @param k
@@ -53,7 +53,7 @@ public SingleLinkedNode<E> reverseLinkedListInAltGroups(SingleLinkedNode<E> node
             i++;
         }
 
-        // recursively call on the next 2k set of nodes
+        // recursively call on the next set of nodes
         if (curr != null) {
             curr.next = reverseLinkedListInAltGroups(curr.next, k);
         }

src/me/ramswaroop/linkedlists/ReverseSingleLinkedList.java

@@ -18,11 +18,9 @@ public class ReverseSingleLinkedList<E extends Comparable<E>> extends SingleLink
      * @param list
      */
     public static <E extends Comparable<E>> void reverseList(SingleLinkedList<E> list) {
-        SingleLinkedNode<E> prev = list.getNode(0);
-        SingleLinkedNode<E> curr = prev.next;
-        prev.next = null; // this will be the last node after reversal, so make next of node = null
+        SingleLinkedNode<E> curr = list.getNode(0), prev = null, next;
         while (curr != null) {
-            SingleLinkedNode<E> next = curr.next;
+            next = curr.next;
             curr.next = prev;
             prev = curr;
             curr = next;