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115 lines (79 loc) · 2.41 KB
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package LeetCode;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;
import LeetCode.InorderStack.TreeNode;
public class SortedArrayToBinarySearchTree {
public static void main(String args[]) throws Exception
{
int[] arr = new int[]{1, 2, 3, 4, 5};
TreeNode root = sortedArrayToBST(arr) ;
List<Integer> result = inorderTraversal(root);
for (int a : result)
{
System.out.print(a + " ");
}
}
public static TreeNode sortedArrayToBST(int[] nums) {
if (nums.length == 0)
{
return null;
}
int start = 0;
int end = nums.length - 1;
return sortedArrayToBSTUtil(nums, start, end);
}
public static TreeNode sortedArrayToBSTUtil(int[] nums, int start, int end) {
if (start > end)
{
return null;
}
int mid = (start + (end - start)/2);
int ele = nums[mid];
TreeNode root = new TreeNode(ele);
root.left = sortedArrayToBSTUtil(nums, start, mid - 1);
root.right = sortedArrayToBSTUtil(nums, mid + 1, end);
return root;
}
static List<Integer> inorderStack(TreeNode root, Stack stack, List<Integer> result)
{
boolean traversalComplete = false;
while (traversalComplete != true)
{
if (root != null)
{
stack.push(root);
root = root.left;
}
else
{
if (stack.isEmpty())
{
traversalComplete = true;
}
else
{
TreeNode popNode = (TreeNode)stack.pop();
//System.out.println("Hey " + popNode.data);
result.add(popNode.data);
root = popNode.right;
}
//stack.push(root);
//if (root != null)
//{
//System.out.println("Hey bbb " + root.data);
//}
}
//if (stack.isEmpty())
//{
//traversalComplete = true;
//}
}
return result;
}
public static List<Integer> inorderTraversal(TreeNode root) {
List<Integer> result = new ArrayList<Integer>();
Stack<TreeNode> stack = new Stack<TreeNode>();
return inorderStack(root, stack, result);
}
}