leetcode-429-N-ary-Tree-Level-Order-Traversal

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描述

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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[
     [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.

分析

已经记不清做了多少道同类型的题了，搞懂 107.
Binary Tree Level Order Traversal II 就够了。

解决方案1(Java)

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/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> children;

    public Node() {}

    public Node(int _val,List<Node> _children) {
        val = _val;
        children = _children;
    }
};
*/
class Solution {
    public List<List<Integer>> levelOrder(Node root) {
        List<List<Integer>> result = new LinkedList<List<Integer>>();
        DFS(root, 0, result);
        return result;
    }
    
    private void DFS(Node node, int i, List<List<Integer>> result) {
        if (node == null) {
            return;
        }
        if (i == result.size()) {
            result.add(result.size(), new LinkedList<Integer>());
        }
        result.get(i).add(node.val);
        for (Node n: node.children) {
            DFS(n, i+1, result);
        }
    }
}

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