Given a n-ary tree, find its maximum depth.node
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.python
For example, given a 3-ary
tree:code
We should return its max depth, which is 3.blog
Note:it
- The depth of the tree is at most
1000
. - The total number of nodes is at most
5000
.
DFS:io
""" # Definition for a Node. class Node(object): def __init__(self, val, children): self.val = val self.children = children """ class Solution(object): def maxDepth(self, root): """ :type root: Node :rtype: int """ if not root: return 0 if not root.children: return 1 depths = [self.maxDepth(node) for node in root.children] return max(depths)+1
簡化下,class
class Solution(object): def maxDepth(self, root): if not root: return 0 if not root.children: return 1 return max(self.maxDepth(node) for node in root.children) + 1
或者是:object
class Solution(object): def maxDepth(self, root): return 1 + max([self.maxDepth(n) for n in root.children] + [0]) if root else 0
BFS:im
""" # Definition for a Node. class Node(object): def __init__(self, val, children): self.val = val self.children = children """ class Solution(object): def maxDepth(self, root): """ :type root: Node :rtype: int """ if not root: return 0 ans = 0 q = [root] while q: ans += 1 q = [c for node in q for c in node.children if c] return ans