LeetCode 515. find the maximum value in each tree row (BFS)

Title Description

You need to find the maximum value in each row of the binary tree.

Thinking

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Code

class TreeNode:
	def __init__(self,x):
		self.val = x
		self.left = None
		self.right = None

class Solution:
	def largestValues(self,root:TreeNode) -> List[int]:
		res = []
		def helper(root,depth):
			if not root:
				return 
			if len(res) == depth:
				res.append([])
			res[depth].append(root.val)
			helper(root.left,depth+1)
			helper(root.right,depth+1)
		helper(root,0)
		ans = []
		for i in res:
			ans.append(max[i])
		return res