题解 | #判断是不是完全二叉树#

    public boolean isCompleteTree (TreeNode root) {
        // write code here
        if(root==null)return true;
        Queue<TreeNode>queue=new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
            int size=queue.size();
            for(int i=0;i<size;i++){
                TreeNode cur=queue.poll();
                if(cur==null){
                    while(!queue.isEmpty())
                        if(queue.poll()!=null)
                            return false;
                    return true;
                }
                queue.offer(cur.left);
                queue.offer(cur.right);
            } 
        }
        return true;
    }