sorted SLL to B BST: almost done

Author: rampatra

src/me/ramswaroop/linkedlists/SortedSLLToBBST.java

@@ -1,5 +1,8 @@
 package me.ramswaroop.linkedlists;
 
+import me.ramswaroop.common.DoubleLinkedList;
+import me.ramswaroop.common.DoubleLinkedNode;
+
 /**
  * Created by IntelliJ IDEA.
  *
@@ -9,11 +12,57 @@
  */
 public class SortedSLLToBBST {
 
-    public void SortedSLLToBBST() {
+    static <E extends Comparable<E>> int getLength(DoubleLinkedNode<E> node) {
+        int l = 0;
+        DoubleLinkedNode<E> curr = node;
+        while (curr != null) {
+            curr = curr.next;
+            l++;
+        }
+        return l;
+    }
 
+    static <E extends Comparable<E>> void inOrder(DoubleLinkedNode<E> node) {
+        if (node == null) return;
+        inOrder(node.prev);
+        System.out.print(node.item.toString());
+        inOrder(node.next);
     }
 
-    public static void main(String a[]) {
+    public static <E extends Comparable<E>> DoubleLinkedNode<E> sortedSLLToBBST(DoubleLinkedNode<E> node) {
+        return sortedSLLToBBST(node, getLength(node));
+    }
+
+    public static <E extends Comparable<E>> DoubleLinkedNode<E> sortedSLLToBBST(DoubleLinkedNode<E> node, int n) {
+        if (n <= 0) {
+            return null;
+        }
+
+        DoubleLinkedNode<E> left = sortedSLLToBBST(node, n / 2);
 
+        DoubleLinkedNode<E> root = node;
+        root.prev = left;
+
+        node = node.next;
+
+        DoubleLinkedNode<E> right = sortedSLLToBBST(node, n - n / 2 - 1);
+        root.next = right;
+
+        return root;
+    }
+
+    public static void main(String a[]) {
+        DoubleLinkedList<Integer> linkedList = new DoubleLinkedList<>();
+        linkedList.add(11);
+        linkedList.add(22);
+        linkedList.add(33);
+        linkedList.add(44);
+        linkedList.add(55);
+        linkedList.add(66);
+        linkedList.add(77);
+        linkedList.printList();
+        inOrder(sortedSLLToBBST(linkedList.head));
+        System.out.println();
+        linkedList.printList();
     }
 }