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POimplementing binary Search tree reconstruction from preOrder array in Java?
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  1. POimplementing binary Search tree reconstruction from preOrder array in Java?
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    copied!<p>I have followed <a href="http://www.careercup.com/question?id=14419694" rel="nofollow">this idea</a> and this <a href="http://ideone.com/VohnS" rel="nofollow">C++ code</a> to reconstruct binary Search Tree from PreOrder array in Java. I am not reinventing the algorithm, but trying to implement pseudocode. I need help here. I do not get the correct output. The output I get is below the code.</p> <pre><code>public class BinaryTreeMethods { public static void main(String[] args) { int[] arr = {7,5,3,6,9,8,10}; Node newone = CreateFromPreOrder(arr,arr.length); printInorder(newone); System.out.println(); printPreOrder(newone); public static Node CreateFromPreOrder(int[] arr, int length) { if(length==0) return null; Node root = new Node(arr[0]); Stack&lt;Node&gt; s = new Stack&lt;Node&gt;(); s.push(root); for(int i=1; i&lt;length; i++) { Node tmp = new Node(arr[i]); Node next = s.peek(); if(tmp.data &lt; next.data) { next.left = tmp; } else { Node popped = null; while(!s.isEmpty() &amp;&amp; tmp.data &gt; next.data) { popped= s.peek(); s.pop(); } popped.right = tmp; } s.push(tmp); } return root; } public static void printInorder(Node root) { if (root!=null){ printInorder(root.left); System.out.print(" " + root.data); printInorder(root.right); } } class Node { Node left; Node right; int data; public Node(int c){ this(c, null, null); } public Node(int c,Node left, Node right) { this.data = c; this.left=left; this.right=right; } } public static void printInorder(Node root) { if (root!=null){ printInorder(root.left); System.out.print(" " + root.data); printInorder(root.right); } } public static void printPreOrder(Node root) { if (root!=null){ System.out.print(" " + root.data); printInorder(root.left); printInorder(root.right); } } } </code></pre> <p>I do not get the expected output:</p> <pre><code>3 5 7 6 8 9 10 7 3 5 6 8 9 10 </code></pre>
 

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