判断是否为满二叉树

public class A {


    class Tree{
        int value;
        Tree left;
        Tree right;

        public Tree(int value) {
            this.value = value;
        }
    }

    //判断是否为满二叉树
    public static boolean isFBT(Tree tree){
        //如果为空，不是满二叉树
        if (null == tree){
            return false;
        }
        boolean isLeaf = false;//是否为叶子节点
        Queue<Tree> queue = new LinkedList<>();
        queue.offer(tree);
        while (!queue.isEmpty()){
            Tree root = queue.poll();
            Tree left = root.left;
            Tree right = root.right;
            //1.右孩子不等于空，左孩子等于空
            //2.当前节点为叶子节点，但是左右节点有不为空的
            if ((null != right && null == left) ||
                    (isLeaf && (null != right || null != left))){
                return false;
            }
            if (null != left){
                queue.offer(left);
            }else if (null != right){
                queue.offer(right);
            }else {
                isLeaf = true;
            }
        }

        return true;
    }
}