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boundary-of-binary-tree.py
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boundary-of-binary-tree.py
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# Time: O(n)
# Space: O(h)
class Solution(object):
def boundaryOfBinaryTree(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
def leftBoundary(root, nodes):
if not root or (not root.left and not root.right):
return
nodes.append(root.val)
if not root.left:
leftBoundary(root.right, nodes)
else:
leftBoundary(root.left, nodes)
def rightBoundary(root, nodes):
if not root or (not root.left and not root.right):
return
if not root.right:
rightBoundary(root.left, nodes)
else:
rightBoundary(root.right, nodes)
nodes.append(root.val)
def leaves(root, nodes):
if not root:
return
if not root.left and not root.right:
nodes.append(root.val)
return
leaves(root.left, nodes)
leaves(root.right, nodes)
if not root:
return []
nodes = [root.val]
leftBoundary(root.left, nodes)
leaves(root.left, nodes)
leaves(root.right, nodes)
rightBoundary(root.right, nodes)
return nodes