# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def largestValues(self, root: Optional[TreeNode]) -> List[int]:
rows = []
q = deque()
q.append(root)
count = len(q)
while q:
current_row = []
count = len(q)
for i in range(count):
node = q.popleft()
if node:
q.append(node.left)
q.append(node.right)
current_row.append(node.val)
if len(current_row):
rows.append(current_row)
# print(rows)
return [max(row) for row in rows]