Invert Tree

InvertTree.java

package com.interviewbytes.trees;

import java.util.Deque;
import java.util.LinkedList;

public class InvertTree {

    public TreeNode invertTree(TreeNode root) {

        if (root == null) return null;

        Deque<TreeNode> queue = new LinkedList<>();
        queue.offer(root);

        while (!queue.isEmpty()) {
            TreeNode node = queue.poll();
            TreeNode temp = node.left;
            node.left = node.right;
            node.right = temp;

            if (node.left != null) queue.offer(node.left);
            if (node.right != null) queue.offer(node.right);
        }

        return root;
    }
}

TreeNode.java

package com.interviewbytes.trees;

public class TreeNode {

    int val;
    TreeNode left;
    TreeNode right;

    TreeNode(int x) {
        val = x;
    }
}