[LeetCode] 429. N-ary Tree Level Order Traversal

 Problem : https://leetcode.com/problems/n-ary-tree-level-order-traversal/

BFS Solution:

"""
# Definition for a Node.
class Node:
    def __init__(self, val=None, children=None):
        self.val = val
        self.children = children
"""

class Solution:
    def levelOrder(self, root: 'Node') -> List[List[int]]:
        if not root: return []
        
        queue = [root]
        result = []
        
        while queue:
            result.append([node.val for node in queue])
            queue = [child for node in queue for child in node.children]
        
        return result

DFS Solution:

"""
# Definition for a Node.
class Node:
    def __init__(self, val=None, children=None):
        self.val = val
        self.children = children
"""

class Solution:
    def levelOrder(self, root: 'Node') -> List[List[int]]:
        if not root: return []
        
        result = []
        
        stack = [(root, 0)]
        
        while stack:
            node, level = stack.pop()
            
            if level == len(result):
                result.append([node.val])
            else:
                result[level].append(node.val)
            
            for child in reversed(node.children):
                stack.append((child, level+1))
        
        return result