Iterative approach 2- Symmetric tree

SymmetricIterative2.java

package com.interviewbytes.trees;

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

public class SymmetricIterative2 {

    public boolean isSymmetric(TreeNode root) {

        if (root == null) return true;

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

        while (!queue.isEmpty()) {

            TreeNode leftNode = queue.poll();
            TreeNode rightNode = queue.poll();

            if (leftNode == null && rightNode == null) continue;

            if (leftNode == null || rightNode == null) return false;

            if (leftNode.val != rightNode.val) return false;

            queue.offer(leftNode.left);
            queue.offer(rightNode.right);
            queue.offer(leftNode.right);
            queue.offer(rightNode.left);

        }

        return true;
    }

}

TreeNode.java

package com.interviewbytes.trees;

public class TreeNode {

    int val;
    TreeNode left;
    TreeNode right;

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