# Definition for a binary tree node.
# class TreeNode(object):
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution(object):
def __init__(self):
self.ret = []
def preorderTraversal(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
if root:
self.ret.append(root.val)
self.preorderTraversal(root.left)
self.preorderTraversal(root.right)
return self.ret
class Solution2(object):
def preorderTraversal(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
if not root:
return []
left = self.preorderTraversal(root.left)
right = self.preorderTraversal(root.right)
return [root.val] + left + right
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