/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
public class Codec {
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
if (root == null) return null;
StringBuilder sb = new StringBuilder();
Stack<TreeNode> stack = new Stack<>();
stack.push(root);
while (!stack.isEmpty()) {
TreeNode node = stack.pop();
sb.append(node.val).append(",");
if (node.right != null) stack.push(node.right);
if (node.left != null) stack.push(node.left);
}
return sb.toString();
}
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
if (data == null || data.length() == 0) return null;
String[] arr = data.split(",");
Queue<Integer> queue = new LinkedList<>();
for (String val : arr) {
queue.offer(Integer.parseInt(val));
}
return buildTree(queue);
}
private TreeNode buildTree(Queue<Integer> queue) {
if (queue.isEmpty()) return null;
TreeNode root = new TreeNode(queue.poll());
Queue<Integer> smallerQueue = new LinkedList<>();
while (!queue.isEmpty() && queue.peek() < root.val) smallerQueue.offer(queue.poll());
root.left = buildTree(smallerQueue);
root.right = buildTree(queue);
return root;
}
}
// Your Codec object will be instantiated and called as such:
// Codec codec = new Codec();
// codec.deserialize(codec.serialize(root));