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'''

File: sfo_32-ii_print_a_binary_tree_top-bottom_ii_s1.py

Created Time: 2021-12-09

Author: Krahets (krahets@163.com)

'''

from include import *

# ===== Solution Code =====

class Solution:

def levelOrder(self, root: TreeNode) -> List[List[int]]:

if not root: return []

res, queue = [], collections.deque()

queue.append(root)

while queue:

tmp = []

for _ in range(len(queue)):

node = queue.popleft()

tmp.append(node.val)

if node.left: queue.append(node.left)

if node.right: queue.append(node.right)

res.append(tmp)

return res

# ======= Test Case =======

root = list_to_tree([3, 9, 20, None, None, 15, 7, None, None, None, None])

# ====== Driver Code ======

slt = Solution()

res = slt.levelOrder(root)

print_matrix(res)