把二叉树打印成多行

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    # 返回二维列表[[1,2],[4,5]]
    def Print(self, pRoot):
        # write code here
        if not pRoot:
            return []
        queue = []
        l = []
        queue.append(pRoot)
        while queue:
            size = len(queue)
            row = []
            for i in queue:
                row.append(i.val)
            l.append(row)
            for i in range(size):
                node = queue.pop(0)
                if node.left:
                    queue.append(node.left)
                if node.right:
                    queue.append(node.right)
        return l