429. Sequence traversal of N-forked trees

"""
# Definition for a Node.
class Node(object):
    def __init__(self, val, children):
        self.val = val
        self.children = children
"""
# 建立两个队列：currLayer和nextLayer

class Solution(object):
    def levelOrder(self, root):
        """
        :type root: Node
        :rtype: List[List[int]]
        """
        # if root == None:
        #     return []
        # currLayer = [root]
        # res = []
        # while True:
        #     currVals = []
        #     nextLayer = []
        #     while len(currLayer) > 0:
        #         currNode = currLayer.pop(0)
        #         currVals.append(currNode.val)
        #         for i in  currNode.children:
        #             nextLayer.append(i)
        #     res.append(currVals)
        #     if len(nextLayer) == 0:
        #         return res
        #     currLayer = nextLayer
        
        if not root:
            return []
        res=[]
        stack=[root]
        while stack:
            res.append([node.val for node in stack])
            temp=[]
            for node in stack:
                for n in node.children:
                    temp.append(n)
            stack=temp
        return res