144. Binary Tree Preorder Traversal 先序遍歷二叉樹
阿新 • • 發佈:2018-02-06
reorder oot rec eno right table self. 先序遍歷 self
來自為知筆記(Wiz)
Given a binary tree, return the preorder traversal of its nodes‘ values.
For example:
Given binary tree [1,null,2,3]
,
1 2 / 3
return [1,2,3]
.
Note: Recursive solution is trivial, could you do it iteratively?
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def preorderTraversal(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
res = []
stack = [root]
while stack and stack[0]:
node = stack.pop
()res.append(node.val)
if node.right:
stack.append(node.right)
if node.left:
stack.append(node.left)
return res
來自為知筆記(Wiz)
144. Binary Tree Preorder Traversal 先序遍歷二叉樹