题目
非递归前序遍历
代码
# 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 preorderTraversal(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
res = []
if root == None:
return res
stack = [root]
while len(stack) != 0:
p = stack.pop()
res.append(p.val)
if p.right != None:
stack.append(p.right)
if p.left != None:
stack.append(p.left)
return res
