剑指 Offer 32 - II. 从上到下打印二叉树 II

从上到下按层打印二叉树，同一层的节点按从左到右的顺序打印，每一层打印到一行。

public class Solution {

    public IList> LevelOrder(TreeNode root) {

        List> list=new List>();

        if(root==null)

        {

            return list;

        }

        Queue queue=new Queue();

        queue.Enqueue(root);

        while(queue.Count>0)

        {

            List level=new List();

            for(int cut=queue.Count; cut>0; cut--)

            {

                var cur=queue.Dequeue();

                level.Add(cur.val);

                if(cur.left!=null)

                {

                    queue.Enqueue(cur.left);

                }

                if(cur.right!=null)

                {

                    queue.Enqueue(cur.right);

                }

            }

            list.Add(level);

        }

        return list;

    }

}