python实现树的遍历
时间: 2023-05-19 17:05:28 浏览: 60
树的遍历可以分为三种方式:前序遍历、中序遍历和后序遍历。以下是 Python 实现树的遍历的代码示例:
# 定义树节点类
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
# 前序遍历
def preorderTraversal(root: TreeNode) -> List[int]:
if not root:
return []
res = []
stack = [root]
while stack:
node = stack.pop()
res.append(node.val)
if node.right:
stack.append(node.right)
if node.left:
stack.append(node.left)
return res
# 中序遍历
def inorderTraversal(root: TreeNode) -> List[int]:
if not root:
return []
res = []
stack = []
while stack or root:
while root:
stack.append(root)
root = root.left
node = stack.pop()
res.append(node.val)
root = node.right
return res
# 后序遍历
def postorderTraversal(root: TreeNode) -> List[int]:
if not root:
return []
res = []
stack = [root]
while stack:
node = stack.pop()
if node.left:
stack.append(node.left)
if node.right:
stack.append(node.right)
res.append(node.val)
return res[::-1]