LC 0102 [M] Binary Tree Level Order Traversal - ALawliet/algorithms GitHub Wiki
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# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def levelOrder(self, root: TreeNode) -> List[List[int]]:
if not root: return []
levels = []
Q = deque([root])
while Q:
# enter the current level
level_size = len(Q)
nodes_in_level = []
# range across the level
for _ in range(level_size):
node = Q.popleft()
nodes_in_level.append(node.val)
if node.left:
Q.append(node.left)
if node.right:
Q.append(node.right)
levels.append(nodes_in_level)
return levels