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package tree;

/**

* Created by gouthamvidyapradhan on 25/02/2017. Given an array where elements are sorted in

* ascending order, convert it to a height balanced BST.

*/

public class SortedArrayToBST {

public class TreeNode {

int val;

TreeNode left;

TreeNode right;

TreeNode(int x) {

val = x;

}

}

/**

* Main method

*

* @param args

* @throws Exception

*/

public static void main(String[] args) throws Exception {

int[] A = {1, 2, 3, 4, 5, 6};

new SortedArrayToBST().sortedArrayToBST(A);

}

public TreeNode sortedArrayToBST(int[] nums) {

if (nums.length == 0) return null;

TreeNode root = new SortedArrayToBST().build(0, nums.length - 1, nums);

preorder(root);

return root;

}

private void preorder(TreeNode node) {

if (node != null) {

preorder(node.left);

System.out.println(node.val);

preorder(node.right);

}

}

private TreeNode build(int s, int e, int[] nums) {

if (s > e) return null;

int m = (e - s) / 2;

int node = nums[s + m];

TreeNode root = new TreeNode(node);

if (s == e) return root;

root.left = build(s, s + m - 1, nums);

root.right = build(s + m + 1, e, nums);

return root;

}

}