二叉树层序遍历

/**
 * 二叉树前序遍历
 *
 * @param node 二叉树节点
 */
public static void levelOrderTraveral(TreeNode node) {
    Queue<TreeNode> queue = new LinkedList<TreeNode>();
    queue.offer(node);
    while (!queue.isEmpty()) {
        TreeNode treeNode = queue.poll();
        System.out.println(node.data);
        if (treeNode.leftchild != null) {
            queue.offer(treeNode);
        }
        if (treeNode.rightchild != null) {
            queue.offer(treeNode);
        }
    }
}