leetcode 429 N-ary Tree Level Order Traversal
z
 2019-06-04 21:37:46  

Given an n-ary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).

For example, given a 3-ary tree:

img

We should return its level order traversal:

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2
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[
     [1],
     [3,2,4],
     [5,6]
]

Note:

  1. The depth of the tree is at most 1000.
  2. The total number of nodes is at most 5000.
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class Solution(object):
    
    def helper(self, ans, level, root):
        if len(ans) == level:
            ans.append([])
        ans[level].append(root.val)
        for child in root.children:
            self.helper(ans, level+1, child)
    
    def levelOrder(self, root):
        """
        :type root: Node
        :rtype: List[List[int]]
        """
        ans = []
        if root == None:
            return ans
        self.helper(ans, 0, root)
        return ans